Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 15,872	$ 13,671	[1]
Marketable securities	22,786	27,778	[1]
Prepaid expenses and other current assets	721	965	[1]
Total current assets	39,379	42,414	[1]
Property and equipment, net	22,356	24,361	[1]
Restricted cash	400	400	[1]
Other assets	241	1,307	[1]
Total assets	62,376	68,482	[1]
Current liabilities:
Accounts payable	2,299	2,781	[1]
Accrued clinical trial expenses	176	216	[1]
Other accrued expenses	3,013	3,158	[1]
Deferred revenue	3,776	4,331	[1]
Current portion of contingent consideration liability	7,000	5,300	[1]
Financing obligations	15,009	18,597	[1]
Total current liabilities	31,273	34,383	[1]
Deferred rent	13,451	14,609	[1]
Noncurrent portion of contingent consideration liability	5,800	7,200	[1]
Stockholders' equity:
Preferred stock	0	0	[1]
Common stock	7	6	[1]
Additional paid-in-capital	295,353	278,386	[1]
Other comprehensive income	17	2	[1]
Deficit accumulated during development stage	(283,525)	(266,104)	[1]
Total stockholders' equity	11,852	12,290	[1]
Total liabilities and stockholders' equity	$ 62,376	$ 68,482	[1]

[1] The condensed consolidated balance sheet at December 31, 2010 has been derived from audited consolidated financial statements at that date.