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STOCKHOLDERS' EQUITY (Tables) | 12 Months Ended
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Dec. 31, 2016
STOCKHOLDERS' EQUITY |
Schedule of aggregate option and award activity |
|  |  |  | Outstanding Options
|  | Shares Available For Grant |  | Number of Shares |  | Weighted Average Exercise Price Per Share |  | Weighted Average Remaining Contractual Life (In years) |  | Aggregate Intrinsic Value (In thousands)
Balance at December 31, 2015 |  |  | 12,054,916 |  |  | 17,205,683 |  | $3.29 |  |  |  |
Options granted |  |  | (2,834,000 | ) |  | 2,834,000 |  | $2.56 |  |  |  |
Awards granted |  |  | (21,541 | ) |  | — |  | $ — |  |  |  |
Options exercised |  |  | — |  |  | (328,486 | ) | $1.50 |  |  |  |
Options cancelled/forfeited |  |  | 371,160 |  |  | (585,910 | ) | $5.34 |  |  |  |
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Balance at December 31, 2016 |  |  | 9,570,535 |  |  | 19,125,287 |  | $3.15 |  | 6.65 |  | $3,816
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Options exercisable at December 31, 2016 |  |  |  |  |  | 14,074,457 |  | $2.99 |  | 6.05 |  | $3,718
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Options fully vested and expected to vest at December 31, 2016 |  |  |  |  |  | 18,694,300 |  | $3.14 |  | 6.60 |  | $3,815
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Schedule of information about stock options outstanding by exercise price range | Information about stock options outstanding as of December 31, 2016 is as follows:
|  | Options Outstanding
Exercise Price Range |  | Number of Shares |  | Weighted Average Exercise Price Per Share |  | Weighted Average Remaining Contractual Life (In years)
$1.10 - $1.51 |  |  | 5,668,162 |  | $1.45 |  | 5.89
$1.55 - $2.54 |  |  | 5,017,031 |  | $2.27 |  | 7.25
$2.74 - $5.01 |  |  | 6,347,008 |  | $4.55 |  | 7.28
$5.09 - $9.32 |  |  | 2,093,086 |  | $5.59 |  | 5.36
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$1.10 - $9.32 |  |  | 19,125,287 |  | $3.15 |  | 6.65
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Schedule of aggregate restricted stock activity |
|  | Number of Shares |  | Weighted Average Grant Date Fair Value Per Share |  | Weighted Average Remaining Contractual Term (In years)
Non-vested restricted stock at December 31, 2015 |  |  | 500 |  | $4.65 |  | 0.10
Granted |  |  | 21,541 |  | $2.44 |  |
Vested |  |  | (22,041 | ) | $2.49 |  |
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Non-vested restricted stock at December 31, 2016 |  |  | — |  | $— |  | —
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Summary of allocation of stock-based compensation expense related to share-based payment awards |
|  | Year Ended December 31, |
(In thousands) |  | 2016 |  | 2015 |  | 2014 |
Research and development |  | $ | 1,275 |  | $ | 2,139 |  | $ | 2,545 |
Restructuring charges |  |  | — |  |  | 307 |  |  | — |
General and administrative |  |  | 6,970 |  |  | 5,951 |  |  | 5,113 |
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Stock-based compensation expense included in operating expenses |  | $ | 8,245 |  | $ | 8,397 |  | $ | 7,658 |
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Schedule of assumptions used to estimate the fair value of stock options granted |
|  | 2016 |  | 2015 |  | 2014
Dividend yield |  | 0% |  | 0% |  | 0%
Expected volatility range |  | 0.888 to 0.890 |  | 0.874 to 0.884 |  | 0.898 to 0.922
Risk-free interest rate range |  | 1.21% to 1.38% |  | 1.68% to 1.71% |  | 1.64% to 1.92%
Expected term |  | 5.5 yrs |  | 5.5 yrs |  | 5.5 yrs
Schedule of assumptions used to estimate the fair value of employee stock purchases under the purchase plan |
|  | 2016 |  | 2015 |  | 2014
Dividend yield |  | 0% |  | 0% |  | 0%
Expected volatility range |  | 0.641 to 0.684 |  | 0.654 to 1.392 |  | 0.835 to 1.666
Risk-free interest rate range |  | 0.28% to 0.45% |  | 0.11% to 0.28% |  | 0.06% to 0.15%
Expected term range |  | 6 mos to 12 mos |  | 6 mos to 12 mos |  | 6 mos to 12 mos
Schedule of common stock reserved for future issuance | Common stock reserved for future issuance as of December 31, 2016 is as follows:
Outstanding stock options |  |  | 19,125,287 |
Options and awards available for grant |  |  | 9,570,535 |
Employee stock purchase plan |  |  | 915,115 |
Warrant outstanding |  |  | 537,893 |
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Total |  |  | 30,148,830 |
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