[1] Univ Calif Berkeley, Lawrence Berkeley Lab, Div Life Sci, Berkeley, CA 94720 USA
[2] Univ Calif Berkeley, Dept Mol & Cell Biol, Berkeley, CA 94720 USA
[3] Stanford Univ, Sch Med, Dept Biochem, Stanford, CA 94305 USA
[4] Stanford Univ, Sch Med, Howard Hughes Med Inst, Stanford, CA 94305 USA
[5] Mem Sloan Kettering Canc Ctr, New York, NY 10021 USA