Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 80,304	$ 73,551
Short-term investments	112,187	136,793
Accounts receivable	3,977	2,416
Restricted investment	10,695	0
Other current assets	17,380	35,036
Total Current Assets	224,543	247,796
Restricted cash and investments	783	782
Property and equipment, net of accumulated depreciation of $24,594 and $19,896 as of December 31, 2015 and 2014, respectively	37,344	38,501
Patent costs, net of accumulated amortization of $2,620 and $2,081 as of December 31, 2015 and 2014, respectively	6,642	5,891
Other assets	4,470	2,063
Total Assets	273,782	295,033
Current Liabilities:
Accounts payable	20,234	12,408
Accrued expenses	29,053	17,366
Current portion of long-term debt	5,936	98
Current portion of notes payable	2,493	2,492
Deferred revenue	3,303	3,318
Other current liabilities	1,275	1,185
Total Current Liabilities	62,294	36,867
Long-term debt	14,969	1,476
Notes payable		2,262
Deferred rent and other	6,172	6,775
Total Liabilities	$ 83,435	$ 47,380
Commitments and contingencies
Stockholders’ Equity:
Preferred stock, $.0001 par value, 3,333,333 shares authorized; none issued and outstanding
Common stock, $.0001 par value, 99,000,000 shares authorized; 45,629,529 and 41,311,512 issued and outstanding at December 31, 2015 and 2014, respectively	$ 5	$ 4
Additional paid-in capital	1,089,508	926,769
Accumulated other comprehensive loss	(111)	(95)
Accumulated deficit	(899,055)	(679,025)
Total Stockholders’ Equity	190,347	247,653
Total Liabilities and Stockholders’ Equity	$ 273,782	$ 295,033