1. The Clayton Foundation Laboratories for
Peptide Biology, The Salk Institute for Biological Studies, 10010 N. Torrey
Pines Road, La Jolla, California 92037, United States
2. Department
of Medicine, CURE/Digestive Diseases Center, Digestive Diseases Division,
University of California at Los Angeles, and Veterans Affairs Greater
Los Angeles Healthcare System, Los Angeles, California 90073, United States