Jonathan S. Leff
Managing Director
Warburg Pincus LLC

Mr. Leff has served as a member of the Board since January 2000. He joined Warburg Pincus LLC, a global private equity investment firm, in 1996 and is currently a Managing Director responsible for the firm's investment efforts in biotechnology and pharmaceuticals. Mr. Leff serves on the boards of directors of Allos Therapeutics, Inc., Inspire Pharmaceuticals, Inc. and ZymoGenetics, Inc., all of which are publicly held companies. Mr. Leff also serves on the board of directors of several private companies. Mr. Leff holds an A.B. in Government from Harvard University and an M.B.A. from Stanford University.