[1] Burnham Inst, Program Apoptosis & Cell Death Res, La Jolla, CA 92037 USA
[2] Columbia Univ, Dept Pharmacol, New York, NY 10032 USA
[3] Univ Calif Irvine, Dept Microbiol & Mol Genet, Irvine, CA 92697 USA
[4] MIT, Dept Biol, Cambridge, MA 02139 USA