[1] NCI, HIV Dynam & Replicat Program, Ctr Canc Res, Frederick, MD 21702 USA
[2] NCI, Chem Biol Lab, Ctr Canc Res, Frederick, MD 21702 USA
[3] Salk Inst Biol Studies, Lab Genet, La Jolla, CA 92037 USA
[4] Scripps Res Inst, Dept Integrat Struct & Computat Biol, La Jolla, CA 92037 USA