| 1. Title of Derivative Security (Instr. 4)
 | 2. Date Exercisable and Expiration Date (Month/Day/Year)
 | 3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)
 | 4. Conversion or Exercise Price of Derivative Security | 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)
 | 6. Nature of Indirect Beneficial Ownership (Instr. 5)
 | 
| Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 
| Employee Stock Option (right to buy) | (3) | 03/16/2024 | Common Stock | 192,994 | $
                5.88 | D |  | 
| Employee Stock Option (right to buy) | (4) | 04/29/2025 | Common Stock | 100,000 | $
                9.17 | D |  | 
| Employee Stock Option (right to buy) | (5) | 02/10/2026 | Common Stock | 147,492 | $
                5.08 | D |  | 
| * | If the form is filed by more than one reporting person, see Instruction 5(b)(v). | 
| ** | Intentional misstatements or omissions of facts constitute Federal Criminal Violations.  See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a). | 
| (1) | 25,000 shares are represented by restricted stock units (each, an RSU). Each RSU represents a contingent right to receive one share upon settlement. 25% of these RSUs vest on April 30, 2016, and 1/48 of these RSUs vest monthly thereafter, subject to the Reporting Person's continued service through each vesting date. | 
| (2) | 62,500 shares are represented by RSUs. Each RSU represents a contingent right to receive one share upon settlement. 25% of these RSUs vest on February 11, 2017, and the remaining RSUs vest in equal quarterly installments thereafter, subject to the Reporting Person's continued service through each vesting date. | 
| (3) | The original option grant of 215,000 shares was exercised for an aggregate of 22,006 shares.  25% of the shares subject to the original option grant vested on March 10, 2015, and 1/48 of the shares vest monthly thereafter, subject to the Reporting Person's continued service through each vesting date. | 
| (4) | 25% of the shares subject to the option vest on April 30, 2016, and 1/48 of the shares vest monthly thereafter, subject to the Reporting Person's continued service through each vesting date. | 
| (5) | 25% of the shares subject to the option vest on February 11, 2017, and 1/48 of the shares vest monthly thereafter, subject to the Reporting Person's continued service through each vesting date. |