STOCK-BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2013

STOCK-BASED COMPENSATION

Summary of option activity

	Number of		Weighted Average
	Shares		Exercise Price
Outstanding at December 31, 2012	5,579,042		$	6.68
Granted	1,053,915		1.64
Exercised	(7,550	)	1.82
Forfeited	(142,382	)	3.60
Expired	(340,776	)	9.38
Outstanding at September 30, 2013	6,142,249		5.74
Options exercisable at September 30, 2013	3,573,589		$	7.91
Weighted average grant date fair value of options granted during the nine months ended September 30, 2013			$	1.16

Schedule of assumptions used in determining fair value of stock options granted using the Black-Scholes option pricing model

	Nine Months Ended
	September 30,
	2013	2012
Expected dividend yield	—	—
Risk-free rate	0.71% - 1.90%	0.67% - 1.15%
Expected option term (in years)	6.0	5.3 – 5.5
Volatility	84% - 85%	84% - 87%