INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2015

Expiration of Net Operating Loss Carry Forwards

The California net operating loss carry forwards will expire as follows (in thousands):


Year		Amount
2016		116,600
2017		51,900
2018		140,600
2028 and beyond		258,100

Components of Deferred Tax Assets

Amounts are shown as of December 31 as of each respective year (in thousands):


	2015			2014
Deferred tax assets:
Net operating losses	$	257,900		$	260,600
Research and development credits		33,500			29,000
Capitalized research and development		58,900			45,700
Share-based compensation expense		10,900			6,900
Deferred revenue		4,300			800
Deferred gain on sales leaseback		5,000			7,200
Intangibles		6,900			10,600
Cease-use expense		700			1,100
Fixed assets		400			500
Other		3,900			4,700

Total deferred tax assets		382,400			367,100
Valuation allowance		(382,400	)		(367,100	)

Net deferred tax assets	$	—		$	—

Provision for Income Taxes on Earnings Subject to Income Taxes Differs from Statutory Federal Rate

The provision for income taxes on earnings subject to income taxes differs from the statutory Federal rate at December 31, 2015, 2014 and 2013, due to the following (in thousands):


	2015			2014			2013
Federal income taxes at 35%	$	(31,126	)	$	(21,190	)	$	(16,131	)
State income tax, net of Federal benefit		2			(3,410	)		(2,611	)
Tax effect on non-deductible expenses		172			10			7
Share-based compensation expense		201			91			215
Change in tax rate		10,773			—			—
Expired tax attributes		5,594			315			151
Research credits		(6,638	)		(1,882	)		(3,458	)
Change in valuation allowance		15,029			25,366			20,504
Uncertain tax positions		5,940			621			1,283
Other		53			79			40

	$	—		$	—		$	—

The following table summarizes the activity related to our unrecognized tax benefits (in thousands):


	2015		2014		2013
Balance as of the beginning of the year	$	23,854	$	23,131	$	21,672
Increases related to prior year tax positions		6,636		47		543
Increases related to current year tax positions		2,584		676		916
Expiration of the statute of limitations for the assessment of taxes		—		—		—

Balance as of the end of the year	$	33,074	$	23,854	$	23,131