1. The Department of Molecular and Cell Biology, University of California, Berkeley, MC 3200 LSA, Berkeley, California 94720-3200, United States
2. National Cancer Institute, National Institutes of Health, 37 Convent Drive, Bethesda, Maryland 20892-4256, United States
3. The Small Molecule Discovery Center, University of California, San Francisco, MC2552 Byers Hall S504, 1700 fourth Street, San Francisco, California 94158-2330, United States