<SEC-DOCUMENT>0001144204-19-006659.txt : 20190212
<SEC-HEADER>0001144204-19-006659.hdr.sgml : 20190212
<ACCEPTANCE-DATETIME>20190212163034
ACCESSION NUMBER:		0001144204-19-006659
CONFORMED SUBMISSION TYPE:	SC 13G
PUBLIC DOCUMENT COUNT:		1
FILED AS OF DATE:		20190212
DATE AS OF CHANGE:		20190212
GROUP MEMBERS:		ALTA PARTNERS MANAGEMENT VIII, LLC
GROUP MEMBERS:		DANIEL JANNEY
GROUP MEMBERS:		FARAH CHAMPSI
GROUP MEMBERS:		GUY NOHRA

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SUTRO BIOPHARMA, INC.
		CENTRAL INDEX KEY:			0001382101
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		IRS NUMBER:				452441988
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-90656
		FILM NUMBER:		19591292

	BUSINESS ADDRESS:	
		STREET 1:		310 UTAH AVE., SUITE 150
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080
		BUSINESS PHONE:		650-392-8412

	MAIL ADDRESS:	
		STREET 1:		310 UTAH AVE., SUITE 150
		CITY:			SOUTH SAN FRANCISCO
		STATE:			CA
		ZIP:			94080

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	SUTRO BIOPHARMA INC
		DATE OF NAME CHANGE:	20061127

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Alta Partners VIII, L.P.
		CENTRAL INDEX KEY:			0001399763
		IRS NUMBER:				204774702
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13G

	BUSINESS ADDRESS:	
		STREET 1:		ONE EMBARCADERO CENTER, SUITE 3700
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94111
		BUSINESS PHONE:		415-362-4022

	MAIL ADDRESS:	
		STREET 1:		ONE EMBARCADERO CENTER, SUITE 3700
		CITY:			SAN FRANCISCO
		STATE:			CA
		ZIP:			94111
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13G
<SEQUENCE>1
<FILENAME>tv512846_sc13g.htm
<DESCRIPTION>SC 13G
<TEXT>
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<P STYLE="margin: 0">&nbsp;</P>

<P STYLE="margin: 0"></P>

<!-- Field: Rule-Page --><DIV ALIGN="LEFT" STYLE="margin-top: 6pt; margin-bottom: 3pt"><DIV STYLE="font-size: 1pt; border-top: Black 2pt solid; border-bottom: Black 1pt solid; width: 100%">&nbsp;</DIV></DIV><!-- Field: /Rule-Page -->

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SECURITIES AND EXCHANGE COMMISSION</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Washington, D.C. 20549</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SCHEDULE 13G</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Under the Securities Exchange Act of
1934</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Amendment No. ___)*</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><FONT STYLE="font-size: 14pt"><B><U>Sutro
Biopharma, Inc.</U></B></FONT></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Name of Issuer)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B><U>Common Stock, $0.001 par value per
share</U></B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Title of Class of Securities)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B><U>869367 10 2</U></B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(CUSIP Number)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0 0pt 1in; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B><U>December 31, 2018</U></B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">(Date of Event which Requires Filing of
this Statement)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Check the appropriate box to designate the rule pursuant to
which this Schedule is filed:</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.25in; text-align: left"><FONT STYLE="font-family: Wingdings">&uml;</FONT></TD><TD STYLE="text-align: justify">Rule 13d-1(b)</TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.25in; text-align: left"><FONT STYLE="font-family: Wingdings">&uml;</FONT></TD><TD STYLE="text-align: justify">Rule 13d-1(c)</TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.25in; text-align: left"><FONT STYLE="font-family: Wingdings">x</FONT></TD><TD STYLE="text-align: justify">Rule 13d-1(d)</TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">*The remainder of this cover page shall be filled out for a
reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment
containing information which would alter the disclosures provided in a prior cover page.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">The information required in the remainder of this cover page
shall not be deemed to be &quot;filed&quot; for the purpose of Section 18 of the Securities Exchange Act of 1934 (&quot;Act&quot;)
or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however,
see the Notes)</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 2 of 12 Pages</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>1</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">NAMES OF REPORTING PERSON</FONT></TD></TR>
<TR>
    <TD STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Alta Partners VIII, L.P.</FONT></TD>
    <TD STYLE="vertical-align: top; border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; text-align: center; width: 10%"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>2</B></FONT></TD>
    <TD STYLE="width: 80%"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP</FONT></TD>
    <TD STYLE="width: 10%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>(a)</B></FONT> <FONT STYLE="font: 10pt Wingdings"><B>&uml;</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid"><B>(b) <FONT STYLE="font-family: Wingdings; font-size: 10pt">x</FONT></B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>3</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">SEC USE ONLY</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="text-align: center; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>4</B></FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">CITIZENSHIP OR PLACE OF ORGANIZATION</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Delaware</P></TD>
    <TD STYLE="border-bottom: Black 1pt solid">&nbsp;</TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD ROWSPAN="4" STYLE="vertical-align: top; width: 15%; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>NUMBER OF</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SHARES</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>BENEFICIALLY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>OWNED BY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>EACH</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>REPORTING</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>PERSON</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>WITH</B></P></TD>
    <TD STYLE="width: 10%; font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>5</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE VOTING POWER</FONT></TD>
    <TD STYLE="width: 40%; text-align: left; vertical-align: top">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (a)</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>6</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED VOTING POWER</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">-0-</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>7</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE DISPOSITIVE POWER</FONT></TD>
    <TD STYLE="text-align: left; vertical-align: top">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (a)</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><B>8</B></FONT></TD>
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED DISPOSITIVE POWER</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid; text-align: left; vertical-align: top">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">-0-</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>9</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">1,944,901 (a)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>10</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES *</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>11</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">8.5% (b)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 10%; border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>12</B></FONT></TD>
    <TD STYLE="width: 90%; border-bottom: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">TYPE OF REPORTING PERSON</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">PN</P></TD>
    <TD STYLE="width: 10%; border-bottom: black 1pt solid">&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.5in; text-align: left">(a)</TD><TD STYLE="text-align: justify">Alta Partners VIII, L.P. (&ldquo;AP VIII&rdquo;) has sole
voting and dispositive control over 1,944,901 shares of common stock (&ldquo;Common Stock&rdquo;) of Sutro Biopharma, Inc. (the
&ldquo;Issuer&rdquo;), except that Alta Partners Management VIII, LLC (&ldquo;APM VIII&rdquo;), the general partner of AP VIII,
and Farah Champsi (&ldquo;Champsi&rdquo;), Daniel Janney (&ldquo;Janney&rdquo;) and Guy Nohra (&ldquo;Nohra&rdquo;), managing
directors of AP VIII, may be deemed to share dispositive and voting power over such stock. Additional information about AP VIII
is set forth in Attachment A hereto including that Mr. Janney currently serves as a member of the Board of Directors of the Issuer.</TD>
</TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.5in; text-align: left">(b)</TD><TD STYLE="text-align: justify">The percentage set forth in row (11) is based on the 22,848,184
outstanding shares of Common Stock as of November 9, 2018 as reported in the Issuer&rsquo;s 10-Q for the quarter ended September
30, 2018 as filed with the Securities and Exchange Commission on November 14, 2018. <FONT STYLE="font-family: Times New Roman, Times, Serif">The
information with respect to the shares of Common Stock beneficially owned by the Reporting Persons is provided as of December
31, 2018.</FONT></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify"><FONT STYLE="font-family: Times New Roman, Times, Serif">&nbsp;</FONT></P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 3 of 12 Pages</TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>1</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">NAMES OF REPORTING PERSON</FONT></TD></TR>
<TR>
    <TD STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-size: 10pt">Alta Partners Management VIII, LLC</FONT></TD>
    <TD STYLE="vertical-align: top; border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; text-align: center; width: 10%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>2</B></FONT></TD>
    <TD STYLE="width: 80%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP</FONT></TD>
    <TD STYLE="width: 10%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>(a)</B></FONT> <FONT STYLE="font: 10pt Wingdings"><B>&uml;</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>(b)
    </B></FONT><B><FONT STYLE="font-family: Wingdings; font-size: 10pt">x</FONT></B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>3</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">SEC USE ONLY</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="text-align: center; border-bottom: Black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>4</B></FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">CITIZENSHIP OR PLACE OF ORGANIZATION</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Delaware</P></TD>
    <TD STYLE="border-bottom: Black 1pt solid">&nbsp;</TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD ROWSPAN="4" STYLE="vertical-align: top; width: 15%; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>NUMBER OF</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SHARES</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>BENEFICIALLY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>OWNED BY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>EACH</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>REPORTING</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>PERSON</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>WITH</B></P></TD>
    <TD STYLE="width: 10%; font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>5</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE VOTING POWER</FONT></TD>
    <TD STYLE="width: 40%">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">-0-</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>6</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED VOTING POWER</FONT></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (c)</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>7</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE DISPOSITIVE POWER</FONT></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">-0-</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><B>8</B></FONT></TD>
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED DISPOSITIVE POWER</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (c)</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>9</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">1,944,901 (c)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>10</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES *</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>11</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">8.5% (b)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 10%; border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>12</B></FONT></TD>
    <TD STYLE="width: 90%; border-bottom: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">TYPE OF REPORTING PERSON</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">OO</P></TD>
    <TD STYLE="width: 10%; border-bottom: black 1pt solid">&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: justify">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.5in; text-align: left"><FONT STYLE="font-size: 10pt">(c)</FONT></TD><TD STYLE="text-align: justify"><FONT STYLE="font-size: 10pt">APM VIII is the general partner
of AP VIII and shares voting and dispositive power over the shares of Common Stock held by AP VIII.</FONT></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 4 of 12 Pages</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>1</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">NAMES
    OF REPORTING PERSON</FONT></TD></TR>
<TR>
    <TD STYLE="border-bottom: black 1pt solid"><P STYLE="margin: 0pt 0"><FONT STYLE="font-size: 10pt">Farah Champsi</FONT></P></td>



    <TD STYLE="vertical-align: top; border-bottom: black 1pt solid"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; text-align: center; width: 10%"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>2</B></FONT></TD>
    <TD STYLE="width: 80%"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">CHECK THE APPROPRIATE BOX
    IF A MEMBER OF A GROUP</FONT></TD>
    <TD STYLE="width: 10%"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>(a)</B></FONT> <FONT STYLE="font-family: Wingdings; font-size: 10pt"><B>&uml;</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>(b)
    </B></FONT><B><FONT STYLE="font-family: Wingdings; font-size: 10pt">x</FONT></B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>3</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">SEC
    USE ONLY</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="text-align: center; border-bottom: Black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>4</B></FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid"><P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-size: 10pt">CITIZENSHIP OR PLACE
        OF ORGANIZATION</FONT></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><FONT STYLE="font-size: 10pt">U.S.A.</FONT></P></TD>
    <TD STYLE="border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD ROWSPAN="4" STYLE="vertical-align: top; width: 15%; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>NUMBER OF</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SHARES</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>BENEFICIALLY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>OWNED BY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>EACH</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>REPORTING</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>PERSON</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>WITH</B></P></TD>
    <TD STYLE="width: 10%; font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>5</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE VOTING POWER</FONT></TD>
    <TD STYLE="width: 40%">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">-0-</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>6</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED VOTING POWER</FONT></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (d)</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>7</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE DISPOSITIVE POWER</FONT></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">-0-</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><B>8</B></FONT></TD>
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED DISPOSITIVE POWER</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (d)</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>9</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">1,944,901 (d)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>10</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES *</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>11</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">8.5% (b)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 10%; border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>12</B></FONT></TD>
    <TD STYLE="width: 90%; border-bottom: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">TYPE OF REPORTING PERSON</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">IN</P></TD>
    <TD STYLE="width: 10%; border-bottom: black 1pt solid">&nbsp;</TD></TR>
</TABLE>



<P STYLE="margin: 0">&nbsp;&nbsp;</P>


<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.5in; text-align: left"><FONT STYLE="font-size: 10pt">(d)</FONT></TD><TD STYLE="text-align: justify">Champsi is a managing director of APM VIII and may be deemed
to share voting and dispositive control over the 1,944,901 shares of Common Stock held by AP VIII.</TD>
</TR></TABLE>



<P STYLE="margin: 0">&nbsp;&nbsp;</P>

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<P STYLE="margin: 0"></P>

<P STYLE="margin: 0">&nbsp;</P>

<P STYLE="margin: 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 5 of 12 Pages</TD></TR>
</TABLE>
<P STYLE="margin: 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>1</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">NAMES OF REPORTING PERSON</FONT></TD></TR>
<TR>
    <TD STYLE="border-bottom: black 1pt solid"><P STYLE="margin: 0pt 0"><FONT STYLE="font-size: 10pt">Daniel Janney</font></P>


</TD>
    <TD STYLE="vertical-align: top; border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; text-align: center; width: 10%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>2</B></FONT></TD>
    <TD STYLE="width: 80%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP</FONT></TD>
    <TD STYLE="width: 10%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>(a)</B></FONT> <FONT STYLE="font-family: Wingdings; font-size: 10pt"><B>&uml;</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>(b)
    </B></FONT><B><FONT STYLE="font-family: Wingdings; font-size: 10pt">x</FONT></B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>3</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">SEC USE ONLY</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="text-align: center; border-bottom: Black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>4</B></FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">CITIZENSHIP OR PLACE OF ORGANIZATION</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">U.S.A.</P></TD>
    <TD STYLE="border-bottom: Black 1pt solid">&nbsp;</TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD ROWSPAN="4" STYLE="vertical-align: top; width: 15%; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>NUMBER OF</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SHARES</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>BENEFICIALLY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>OWNED BY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>EACH</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>REPORTING</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>PERSON</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>WITH</B></P></TD>
    <TD STYLE="width: 10%; font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>5</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE VOTING POWER</FONT></TD>
    <TD STYLE="width: 40%">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">3,615 (e)</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>6</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED VOTING POWER</FONT></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (f)</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>7</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE DISPOSITIVE POWER</FONT></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">3,615 (e)</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><B>8</B></FONT></TD>
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED DISPOSITIVE POWER</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (f)</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>9</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">1,948,516</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>10</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES *</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>11</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">8.5% (b)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 10%; border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>12</B></FONT></TD>
    <TD STYLE="width: 90%; border-bottom: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">TYPE OF REPORTING PERSON</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">IN</P></TD>
    <TD STYLE="width: 10%; border-bottom: black 1pt solid">&nbsp;</TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;&nbsp;&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.5in; text-align: left"><FONT STYLE="font-size: 10pt">(e)</FONT></TD><TD STYLE="text-align: justify"><FONT STYLE="font-size: 10pt">Represents shares issuable
pursuant to options that are exercisable within 60 days of December 31, 2018.</FONT></TD>
</TR></TABLE>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.5in; text-align: left"><FONT STYLE="font-size: 10pt">(f)</FONT></TD><TD STYLE="text-align: justify"><FONT STYLE="font-size: 10pt">Janney is a managing director
of APM VIII and may be deemed to share voting and dispositive control over the 1,944,901 shares of Common Stock held by AP VIII.
Mr. Janney is also a member of the Board of Directors of the Issuer.</FONT></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;</P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 6 of 12 Pages</TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;&nbsp;&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-top: black 1pt solid; border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>1</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-top: black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">NAMES OF REPORTING PERSON</FONT></TD></TR>
<TR>
    <TD STYLE="border-bottom: black 1pt solid"><P STYLE="margin: 0pt 0"><FONT STYLE="font-size: 10pt">Guy Nohra</font></P>


</TD>
    <TD STYLE="vertical-align: top; border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; text-align: center; width: 10%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>2</B></FONT></TD>
    <TD STYLE="width: 80%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP</FONT></TD>
    <TD STYLE="width: 10%"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>(a)</B> </FONT><FONT STYLE="font-family: Wingdings; font-size: 10pt"><B>&uml;</B></FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>(b)
    </B></FONT><B><FONT STYLE="font-family: Wingdings; font-size: 10pt">x</FONT></B></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; text-align: center"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>3</B></FONT></TD>
    <TD COLSPAN="2" STYLE="border-bottom: black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif">SEC USE ONLY</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="text-align: center; border-bottom: Black 1pt solid"><FONT STYLE="font: 10pt Times New Roman, Times, Serif"><B>4</B></FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">CITIZENSHIP OR PLACE OF ORGANIZATION</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">U.S.A.</P></TD>
    <TD STYLE="border-bottom: Black 1pt solid">&nbsp;</TD></TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR>
    <TD ROWSPAN="4" STYLE="vertical-align: top; width: 15%; border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>NUMBER OF</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SHARES</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>BENEFICIALLY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>OWNED BY</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>EACH</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>REPORTING</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>PERSON</B></P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>WITH</B></P></TD>
    <TD STYLE="width: 10%; font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>5</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE VOTING POWER</FONT></TD>
    <TD STYLE="width: 40%">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">-0-</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>6</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED VOTING POWER</FONT></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (g)</P></TD></TR>
<TR>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>7</B></FONT></TD>
    <TD STYLE="font-size: 10pt; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SOLE DISPOSITIVE POWER</FONT></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">-0-</P></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><B>8</B></FONT></TD>
    <TD STYLE="font-size: 10pt; border-bottom: Black 1pt solid; text-align: left; vertical-align: top"><FONT STYLE="font-size: 10pt">SHARED DISPOSITIVE POWER</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">1,944,901 (g)</P></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%">
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>9</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt">1,944,901 (g)</TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>10</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES *</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD ROWSPAN="2" STYLE="border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>11</B></FONT></TD>
    <TD COLSPAN="2" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="border-bottom: black 1pt solid; font-size: 10pt"><FONT STYLE="font-size: 10pt">8.5% (b)</FONT></TD>
    <TD STYLE="border-bottom: black 1pt solid">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 10%; border-bottom: black 1pt solid; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 10pt"><B>12</B></FONT></TD>
    <TD STYLE="width: 90%; border-bottom: black 1pt solid">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">TYPE OF REPORTING PERSON</P>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">IN</P></TD>
    <TD STYLE="width: 10%; border-bottom: black 1pt solid">&nbsp;</TD></TR>
</TABLE>





<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0; margin-bottom: 0; width: 100%"><TR STYLE="vertical-align: top; text-align: justify">
<TD STYLE="width: 0"></TD><TD STYLE="width: 0.5in; text-align: left"><FONT STYLE="font-size: 10pt">(g)</FONT></TD><TD STYLE="text-align: justify"><FONT STYLE="font-size: 10pt">Nohra is a managing director
of APM VIII and may be deemed to share voting and dispositive control over the 1,944,901 shares of Common Stock held by AP VIII.</FONT></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt">&nbsp;&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 7 of 12 Pages</TD></TR>
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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR>
    <TD COLSPAN="3" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>Item 1.</B></FONT></TD>
    </TR>
<TR>
    <TD STYLE="width: 0.5in">&nbsp;</TD>
    <TD STYLE="vertical-align: top; width: 0.5in; font-size: 10pt"><FONT STYLE="font-size: 10pt">(a)</FONT></TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Name of Issuer:</FONT><BR>
<FONT STYLE="font-size: 10pt">Sutro Biopharma, Inc. (&ldquo;Issuer&rdquo;)</FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid; font-size: 10pt">&nbsp;</TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt"><FONT STYLE="font-size: 10pt">(b)</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid"><P STYLE="margin-top: 0; margin-bottom: 0">Address of Issuer&rsquo;s Principal Executive Offices:<BR> 310 Utah Avenue, Suite 150</P>
                                               <P STYLE="margin-top: 0; margin-bottom: 0">South San Francisco, CA&nbsp; 94080</P>
                                               <P STYLE="margin-top: 0; margin-bottom: 0">&nbsp;</P></TD>
    </TR>
<TR>
    <TD COLSPAN="3">&nbsp;</TD>
    </TR>
<TR>
    <TD COLSPAN="3" STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt"><B>Item 2.</B></FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt"><FONT STYLE="font-size: 10pt">(a)</FONT></TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Name of Person Filing:</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Alta Partners VIII, L.P. (&ldquo;APVIII&rdquo;)</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Alta Partners Management VIII, LLC (&ldquo;APMVIII&rdquo;)</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Guy Nohra (&ldquo;GN&rdquo;)</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Daniel Janney (&ldquo;DJ&rdquo;)</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Farah Champsi (&ldquo;FC&rdquo;)</FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid">&nbsp;</TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt"><FONT STYLE="font-size: 10pt">(b)</FONT></TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Address of Principal Business Office:</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">One Embarcadero Center, Suite 3700</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">San Francisco, CA 94111</FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid">&nbsp;</TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt"><FONT STYLE="font-size: 10pt">(c)</FONT></TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Citizenship/Place of Organization:</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt">&nbsp;</TD></TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Entities:&nbsp;&nbsp;&nbsp;</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">APVIII&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;-&nbsp;&nbsp;&nbsp;&nbsp;Delaware</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">APMVIII&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;-&nbsp;&nbsp;&nbsp;&nbsp;Delaware</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Individuals:</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">DJ&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;-&nbsp;&nbsp;&nbsp;United States</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">GN&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;-&nbsp;&nbsp;&nbsp;United States</FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">FC&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;-&nbsp;&nbsp;&nbsp;United States</FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt">&nbsp;</TD></TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt"><FONT STYLE="font-size: 10pt">(d)</FONT></TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Title of Class of Securities:</FONT></TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">Common Stock, $0.001 par value per share</FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid">&nbsp;</TD>
    </TR>
<TR>
    <TD STYLE="font-size: 10pt">&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt"><FONT STYLE="font-size: 10pt">(e)</FONT></TD>
    <TD STYLE="font-size: 10pt"><FONT STYLE="font-size: 10pt">CUSIP Number:</FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD STYLE="vertical-align: top; font-size: 10pt">&nbsp;</TD>
    <TD STYLE="border-bottom: Black 1pt solid; font-size: 10pt"><P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-size: 10pt">869367 10 2</FONT></P>
                                                                <P STYLE="margin-top: 0; margin-bottom: 0"><FONT STYLE="font-size: 10pt">&nbsp;</FONT></P></TD>
    </TR>
<TR>
    <TD COLSPAN="3">&nbsp;</TD>
    </TR>
</TABLE>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 8 of 12 Pages</TD></TR>
</TABLE>
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<TD STYLE="width: 0%"></TD><TD STYLE="width: 0.5in; text-align: left"><FONT STYLE="font-size: 10pt"><B>Item 3.</B></FONT></TD><TD STYLE="text-align: justify"><FONT STYLE="font-size: 10pt"><B>Not applicable.</B></FONT></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;
&nbsp;&nbsp;</P>

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<TD STYLE="width: 0%"></TD><TD STYLE="width: 0.5in; text-align: left"><B>Item 4</B>.</TD><TD STYLE="text-align: justify"><B>Ownership.</B></TD>
</TR></TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">The following beneficial ownership information is provided as
of December 31, 2018.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Please see Attachment A</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;</B></P>

<TABLE CELLPADDING="0" CELLSPACING="0" STYLE="border-collapse: collapse; width: 100%; font: 10pt Times New Roman, Times, Serif">
<TR STYLE="vertical-align: bottom">
    <TD NOWRAP STYLE="font-weight: bold">Fund Entities</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center"><P STYLE="margin-top: 0; margin-bottom: 0">Shares</P>
                                                                         <P STYLE="margin-top: 0; margin-bottom: 0">Held<BR>
Directly</P></TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">Sole<BR>
Voting<BR>
Power</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">Shared<BR>
Voting<BR>
Power</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">Sole<BR>
Dispositive<BR>
Power</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">Shared<BR>
Dispositive<BR>
Power</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">Beneficial<BR>
Ownership</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">Percentage<BR>
of Class</TD><TD STYLE="font-weight: bold">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom">
    <TD NOWRAP STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD>
    <TD NOWRAP COLSPAN="2" STYLE="font-weight: bold; text-align: center">&nbsp;</TD><TD STYLE="font-weight: bold">&nbsp;</TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD STYLE="width: 23%">APVIII</TD><TD STYLE="width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 8%; text-align: right">1,944,901</TD><TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 8%; text-align: right">0</TD><TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 8%; text-align: right">1,944,901</TD><TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 8%; text-align: right">0</TD><TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 8%; text-align: right">1,944,901</TD><TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 8%; text-align: right">1,944,901</TD><TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 1%">&nbsp;</TD>
    <TD STYLE="width: 1%; text-align: left">&nbsp;</TD><TD STYLE="width: 8%; text-align: right">8.5</TD><TD STYLE="width: 1%; text-align: left">%</TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD>APMVIII</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">8.5</TD><TD STYLE="text-align: left">%</TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD>DJ</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">3,615</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">3,615</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,948,516</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">8.5</TD><TD STYLE="text-align: left">%</TD></TR>
<TR STYLE="vertical-align: bottom; background-color: White">
    <TD>GN</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">8.5</TD><TD STYLE="text-align: left">%</TD></TR>
<TR STYLE="vertical-align: bottom; background-color: rgb(204,238,255)">
    <TD>FC</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">0</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">1,944,901</TD><TD STYLE="text-align: left">&nbsp;</TD><TD>&nbsp;</TD>
    <TD STYLE="text-align: left">&nbsp;</TD><TD STYLE="text-align: right">8.5</TD><TD STYLE="text-align: left">%</TD></TR>
</TABLE>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B></B></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR>
    <TD STYLE="width: 0.5in">
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Item 5.</B></P></TD>
    <TD>
        <P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>Ownership of Five Percent or Less of a Class</B></P></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    </TR>
<TR>
    <TD COLSPAN="2"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than 5 percent of the class of securities, check the following </FONT><FONT STYLE="font-family: Wingdings; font-size: 10pt">&uml;</FONT></TD>
    </TR>
<TR>
    <TD COLSPAN="2">&nbsp;</TD>
    </TR>
<TR>
    <TD><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>Item 6.</B></FONT></TD>
    <TD><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>Ownership of More than Five Percent on Behalf of Another Person</B></FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR>
    <TD COLSPAN="2"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Not applicable.</FONT></TD>
    </TR>
<TR>
    <TD COLSPAN="2">&nbsp;</TD>
    </TR>
<TR>
    <TD STYLE="vertical-align: top"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>Item 7.</B></FONT></TD>
    <TD><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company.</B></FONT></TD>
    </TR>
<TR>
    <TD STYLE="vertical-align: top">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR>
    <TD COLSPAN="2"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Not applicable.</FONT></TD>
    </TR>
<TR>
    <TD COLSPAN="2">&nbsp;</TD>
    </TR>
<TR>
    <TD><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>Item 8.</B></FONT></TD>
    <TD><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>Identification and Classification of Members of the Group</B></FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR>
    <TD COLSPAN="2"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">No reporting person is a member of a group as defined in Section 240.13d-1(b)(1)(ii)(J) of the Act.</FONT></TD>
    </TR>
<TR>
    <TD COLSPAN="2">&nbsp;</TD>
    </TR>
<TR>
    <TD><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>Item 9.</B></FONT></TD>
    <TD><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt"><B>Notice of Dissolution of Group</B></FONT></TD>
    </TR>
<TR>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR>
    <TD COLSPAN="2"><FONT STYLE="font-family: Times New Roman, Times, Serif; font-size: 10pt">Not applicable.</FONT></TD>
    </TR>
</TABLE>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>&nbsp;&nbsp;</B></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR>
    <TD STYLE="width: 0.5in"><FONT STYLE="font-size: 10pt"><B>Item 10.</B></FONT></TD>
    <TD><FONT STYLE="font-size: 10pt"><B>Certification</B></FONT></TD></TR>
<TR>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR>
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">Not applicable.</FONT></TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>


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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 9 of 12 Pages</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"><B>EXHIBITS</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">A: Joint Filing Statement</P>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 10 of 12 Pages</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>SIGNATURE<BR>
<BR>
</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">After reasonable inquiry and to the best
of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.<BR>
</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><FONT STYLE="font-size: 10pt">Date: </FONT> <FONT STYLE="font-size: 10pt">February 12, 2019</FONT></P>


<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt"><B>Alta Partners VIII, L.P.</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">By: Alta Partners Management VIII, LLC</FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 3%; padding-bottom: 1pt"><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD STYLE="width: 47%; border-bottom: Black 1pt solid"> <FONT STYLE="font-size: 10pt">/s/ Daniel Janney</FONT></TD>
    <TD STYLE="width: 50%; padding-bottom: 1pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD STYLE="padding-left: 0.125in"><FONT STYLE="font-size: 10pt">Daniel Janney, Managing Director</FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt"><B>Alta Partners Management VIII, LLC</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid"> <FONT STYLE="font-size: 10pt">/s/ Daniel Janney</FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD STYLE="padding-left: 0.125in"><FONT STYLE="font-size: 10pt">Daniel Janney, Managing Director</FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><U STYLE="text-decoration: none">/s/ Daniel Janney</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="padding-left: 0.375in"><FONT STYLE="font-size: 10pt"><B>Daniel Janney</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><U STYLE="text-decoration: none">/s/ Guy Nohra</U></FONT></TD>
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="padding-left: 0.375in"><FONT STYLE="font-size: 10pt"><B>Guy Nohra</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><U STYLE="text-decoration: none">/s/ Farah Champsi</U></FONT></TD>
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="padding-left: 0.375in"><FONT STYLE="font-size: 10pt"><B>Farah Champsi</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;</P>

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    <DIV STYLE="page-break-before: always; margin-top: 6pt; margin-bottom: 12pt">&nbsp;</DIV>
    <!-- Field: /Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 11 of 12 Pages</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>&nbsp;&nbsp;</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>EXHIBIT A</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>AGREEMENT OF JOINT FILING</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">We, the undersigned, hereby express our
agreement that the attached Schedule 13G is filed on behalf of us.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin-top: 0pt; margin-bottom: 0pt"><FONT STYLE="font-size: 10pt">Date: </FONT> <FONT STYLE="font-size: 10pt">&nbsp;February 12, 2019</FONT></P>



<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt"><B>Alta Partners VIII, L.P.</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt">By: Alta Partners Management VIII, LLC</FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 3%; padding-bottom: 1pt"><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD STYLE="width: 47%; border-bottom: Black 1pt solid"> <FONT STYLE="font-size: 10pt">/s/ Daniel Janney</FONT></TD>
    <TD STYLE="width: 50%; padding-bottom: 1pt">&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD STYLE="padding-left: 0.125in"><FONT STYLE="font-size: 10pt">Daniel Janney, Managing Director</FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2"><FONT STYLE="font-size: 10pt"><B>Alta Partners Management VIII, LLC</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD><FONT STYLE="font-size: 10pt">By:</FONT></TD>
    <TD STYLE="border-bottom: Black 1pt solid"> <FONT STYLE="font-size: 10pt">/s/ Daniel Janney</FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD>&nbsp;</TD>
    <TD STYLE="padding-left: 0.125in"><FONT STYLE="font-size: 10pt">Daniel Janney, Managing Director</FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><U STYLE="text-decoration: none">/s/ Daniel Janney</U></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="padding-left: 0.375in"><FONT STYLE="font-size: 10pt"><B>Daniel Janney</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><U STYLE="text-decoration: none">/s/ Guy Nohra</U></FONT></TD>
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="padding-left: 0.375in"><FONT STYLE="font-size: 10pt"><B>Guy Nohra</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2">&nbsp;</TD>
    <TD>&nbsp;</TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="border-bottom: Black 1pt solid"><FONT STYLE="font-size: 10pt"><U STYLE="text-decoration: none">/s/ Farah Champsi</U></FONT></TD>
    <TD><FONT STYLE="font-size: 10pt">&nbsp;</FONT></TD></TR>
<TR STYLE="vertical-align: top">
    <TD COLSPAN="2" STYLE="padding-left: 0.375in"><FONT STYLE="font-size: 10pt"><B>Farah Champsi</B></FONT></TD>
    <TD>&nbsp;</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-indent: 0.5in"></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0"></P>

<TABLE CELLSPACING="0" CELLPADDING="0" STYLE="font: 10pt Times New Roman, Times, Serif; width: 100%; border-collapse: collapse">
<TR STYLE="vertical-align: top">
    <TD STYLE="width: 40%; font-size: 10pt; text-align: left"><FONT STYLE="font-size: 10pt">CUSIP No.&nbsp;869367 10 2</FONT></TD>
    <TD STYLE="width: 20%; font-size: 10pt; text-align: center"><FONT STYLE="font-size: 12pt"><B>13G</B></FONT></TD>
    <TD STYLE="width: 40%; font-size: 10pt; text-align: right">Page 12 of 12 Pages</TD></TR>
</TABLE>
<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;&nbsp;&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"></P>

<!-- Field: Rule-Page --><DIV ALIGN="LEFT"><DIV STYLE="font-size: 1pt; border-top: Black 1pt solid; width: 100%">&nbsp;</DIV></DIV><!-- Field: /Rule-Page -->

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center"><B>Attachment A</B></P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0; text-align: center">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Alta Partners VIII, L.P. beneficially owns 1,944,901 shares
of Common Stock and exercises sole voting and dispositive control over such shares, except to the extent set forth below.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Alta Partners Management VIII, LLC is the general partner of
Alta Partners VIII, L.P. and may be deemed to share the right to direct the voting and dispositive control over the shares held
by such fund.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Mr. Daniel Janney is a managing director of Alta Partners Management
VIII, LLC and may be deemed to share the right to direct the voting and dispositive control over the shares held by such fund.
Mr. Janney also serves as a member of the Board of Directors of the Issuer.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Mr. Guy Nohra is a managing director of Alta Partners Management
VIII, LLC and may be deemed to share the right to direct the voting and dispositive control over the shares held by such fund.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">Ms. Farah Champsi is a managing director of Alta Partners Management
VIII, LLC and may be deemed to share the right to direct the voting and dispositive control over the shares held by such fund.</P>

<P STYLE="font: 10pt Times New Roman, Times, Serif; margin: 0pt 0">&nbsp;</P>

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