Exhibit 99.1

Signatures for Form 4

	QUEST DIAGNOSTICS INCORPORATED
	By:	/s/ William J. O’Shaughnessy, Jr.
	Name:	William J. O’Shaughnessy, Jr.
	Title:	Assistant General Counsel and Secretary
	Date:	May 12, 2011

	SPARK ACQUISITION CORPORATION
	By:	/s/ Robert A. Hagemann
	Name:	Robert A. Hagemann
	Title:	President
	Date:	May 12, 2011