[1] Univ Calif San Diego, Mol Biol, La Jolla, CA 92093 USA
[2] Univ Munich, Gene Ctr, Munich, Germany
[3] Univ Oxford, Sir William Dunn Sch Pathol, Oxford, England
[4] Stanford Univ, Dev Biol, Stanford, CA 94305 USA
[5] Univ Calif San Diego, Chem & Biochem, La Jolla, CA 92093 USA
[6] Univ Calif San Diego, Sch Med, Natl Ctr Microscopy & Imaging Res, La Jolla, CA 92093 USA
[7] Univ Calif San Diego, Div Biol Sci, San Diego, CA 92103 USA