1. Laboratory of Cell And Developmental Signaling, National Cancer Institute, Frederick, MD 21702;
2. Program in Gene Function and Expression, University of Massachusetts Medical School, Worcester, MA 01605;
3. Department of Biotechnology, Graduate School of Engineering, Osaka University, Osaka 565–0871, Japan;
4. EM Facility/Image Analysis Laboratory, SAIC, Frederick, MD 21702; and
5. Neurobiology Unit, Ecole Superieure de Physique et Chimie Industrielles, CNRS, 75005 Paris, France