STOCKHOLDERS' EQUITY (Tables)

12 Months Ended

Dec. 31, 2014

Stock-based compensation expense recognized under ASC 718 was as follows:

	December 31,
	2014		2013		2012
Research and development	$	-	$	92,249	$	171,217
General and administrative		21,416		19,387		57,268
Total stock-based compensation expense	$	21,416	$	111,636	$	228,485

The following table presents the assumptions used to estimate the fair values of the stock options granted in the periods presented:

The summary of the stock options activity is as follows for year ended:

	Shares			Weighted-Average Exercise Price		Weighted-Average Remaining Contractual Term		Aggregate Intrinsic Value
Outstanding at January 1, 2013		1,182,000		$	8.90		4.49	$	9,597,000
Grants		30,000			16.88		10.00		-
Exercised		(30,000	)		1.00		-		602,100
Forfeitures or expirations		(15,000	)		30.79		-		-
Outstanding at January 1, 2014		1,167,000			9.03		3.65		15,420,965
Grants		15,000			26.48		10.00		-
Exercised		(407,042	)		5.27		-		11,559,689
Forfeitures or expirations		(15,000	)		26.48		-		-
Outstanding at December 31, 2014		759,958			11.04		3.12		23,483,235

Vested and expected to vest at December 31, 2014		728,708			10.43		2.99		20,542,279
Exercisable at December 31, 2014		728,708		$	10.43		2.99	$	20,542,279

The following table summarizes information relating to stock options by exercise price at December 31, 2014:

		Outstanding Shares						Exercisable Shares
Option Exercise Price		Number of Shares		Weighted Average Life (years)		Weighted Average Exercise Price		Number of Shares	Weighted Average Option Price		Weighted Average Life (years)
	$0.83 - 1.00		247,500		1.38		$0.91	247,500		$0.91		1.38
	4.00 - 5.50		133,000		2.51		4.78	133,000		4.78		2.51
	13.24 - 15.85		121,958		4.46		14.05	121,958		14.05		4.46
	17.00 - 21.00		167,500		4.30		19.50	156,250		19.61		3.98
	26.43 - 29.21		90,000		4.84		28.28	70,000		28.02		4.82
			759,958		3.12		$11.04	728,708		$10.43		2.99