During the first quarter of 2011, certain outside investors exercised 1,578,948 Series CC warrants in exchange for issuance of 1,578,948 shares of our common stock, resulting in gross proceeds of $3,331,580. Also during the first quarter of 2011, certain outside investors exercised 799,474 Series DD warrants in exchange for issuance of 799,474 shares of our common stock, resulting in gross proceeds of $1,686,890. In addition, another outside investor exercised 60,000 Series Z warrants on a cashless basis in exchange for issuance of 46,902 shares of our common stock during the first quarter of 2011.

At March 31, 2012, there are 17.6 million warrants outstanding to purchase our common stock. The warrants are exercisable at prices ranging from $0.31 to $2.375 per share with a weighted average exercise price of $0.56 per share.