[1] Mem Sloan Kettering Canc Ctr, Dev Biol Program, New York, NY 10065 USA
[2] Cornell Univ, Weill Med Coll, Dept Pharmacol, New York, NY 10065 USA
[3] Columbia Univ, Dept Physiol & Cellular Biophys, New York, NY 10032 USA
[4] Univ Calif San Francisco, Sch Med, Dept Neurol, San Francisco, CA 94143 USA
[5] Univ Calif San Francisco, Howard Hughes Med Inst, Dept Physiol, San Francisco, CA 94143 USA
[6] Univ Calif San Francisco, Howard Hughes Med Inst, Dept Biochem, San Francisco, CA 94143 USA
[7] Univ Calif San Francisco, Howard Hughes Med Inst, Dept Biophys, San Francisco, CA 94143 USA