<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>e602964_ex24.txt
<TEXT>

                                POWER OF ATTORNEY

      Known by all these presents, that each of the undersigned hereby
constitutes and appoints James Mannix, as such undersigned's true and lawful
attorney-in-fact to:

(1)   execute for and on behalf of such undersigned's Forms 3, 4 and 5 in
      accordance with Section 16(a) of the Securities Exchange Act of 1934 and
      the rules thereunder, and any other forms or reports each of the
      undersigned may be required to file in connection with such undersigned's
      ownership, acquisition, or disposition of securities;

(2)   do and perform any and all acts for and on behalf of each of the
      undersigned which may be necessary or desirable to complete and execute
      any such Form 3, 4 or 5, or other form or report, and timely file such
      form or report with the United States Securities and Exchange Commission
      and any stock exchange or similar authority; and

(3)   take any other action of any type whatsoever in connection with the
      forgoing which, in the opinion of such attorney-in-fact, may be of benefit
      to, in the best interest of, or legally required by, each of the
      undersigned, it being understood that the documents executed by such
      attorney-in-fact on behalf of each of the undersigned pursuant to this
      Power of Attorney shall be in such form and shall contain such terms and
      conditions as such attorney-in-fact may approve in such attorney-in-fact's
      discretion.

      Each of the undersigned hereby grants to such attorney-in-fact full power
and authority to do and perform any and every act and thing whatsoever
requisite, necessary, or proper to be done in the exercise of any of the rights
and powers herein granted, as fully to all intents and purposes as each of the
undersigned might or could do if personally present, with full power of
substitution or revocation, hereby ratifying and confirming all that such
attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall
lawfully do or cause to be done by virtue of this power of attorney and the
rights and powers herein granted. Each of the undersigned acknowledge that the
forgoing attorney-in-fact, in serving in such capacity at the request of each of
the undersigned, is not assuming any of the undersigned's responsibilities to
comply with Section 16 of the Securities Exchange Act of 1934.

      This Power of Attorney shall remain in full force and effect until such
undersigned is no longer subject to Section 16(a) under the Securities and
Exchange Act of 1934 and the rules and regulations promulgated thereunder,
unless earlier revoked by such undersigned in a signed writing delivered to the
foregoing attorney-in-fact.

<PAGE>

      IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed this 10th day of January, 2007.

                             PERCEPTIVE LIFE SCIENCES MASTER FUND LTD.


                             /s/ Joseph Edelman
                             ---------------------------------------------------
                             By: Perceptive Advisors LLC, its investment manager
                             Name:  Joseph Edelman
                             Title: Managing Member


                             PERCEPTIVE ADVISORS LLC


                             /s/ Joseph Edelman
                             ---------------------------------------------------
                             Name:  Joseph Edelman
                             Title: Managing Member


                             /s/ Joseph Edelman
                             ---------------------------------------------------
                             JOSEPH EDELMAN


                             /s/ Michael Cho
                             ---------------------------------------------------
                             Michael Cho


                             /s/ Scott Bradley
                             ---------------------------------------------------
                             Scott Bradley
</TEXT>
</DOCUMENT>
