[1] Univ Calif San Francisco, Dept Immunol & Microbiol, GW Hooper Fdn, San Francisco, CA 94143 USA
[2] Univ Calif San Francisco, Dept Biopharmaceut Sci, San Francisco, CA 94143 USA
[3] Univ Calif San Francisco, Dept Pharmaceut Chem, San Francisco, CA 94143 USA
[4] Univ Calif San Francisco, Dept Physiol, San Francisco, CA 94143 USA
[5] Univ Calif San Francisco, Dept Neurol, San Francisco, CA 94143 USA
[6] Univ Calif San Francisco, Dept Anat, San Francisco, CA 94143 USA
[7] Fred Hutchinson Canc Res Ctr, Div Basic Sci, Seattle, WA 98109 USA