The Board originally adopted the Plan with stockholder approval in May 2006. The Board subsequently amended the Plan from time to time, with stockholder approval, to increase the number of Shares authorized for issuance under the Plan to 3,058,734. On March 23, 2016, the Board amended the Plan, subject to stockholder approval, to increase the number of Shares authorized for issuance by an additional 1,500,000 shares, bringing the total number of Shares subject to the Plan to 4,558,734.