1. The Burnham Institute, Program on Apoptosis and Cell Death Research, 10901 North Torrey Pines Road, La Jolla, California 92037, Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, Idun Pharmaceuticals, 11085 North Torrey Pines Road, La Jolla, California 92037, and Center for Apoptosis Research, Kimmel Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107