1. Adolor Corporation, 700 Pennsylvania Drive, Exton, Pennsylvania 19341, Semafore Pharmaceuticals Inc., 8496 Georgetown Road, Indianapolis, Indiana 46268, NIH Chemical Genomics Center, National Human Genome Research Institute, National Institutes of Health, 9800 Medical Center Drive, Rockville, Maryland 20850, and Department of Chemistry, University of Massachusetts, 100 Morrissey Boulevard, Boston, Massachusetts 02125