1. Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093–0723, USA.
2. Laboratory of Mucosal Immunology, Departments of Medicine and Pediatrics, School of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093–0723, USA.
3. Program on Cell Adhesion, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.