Drug Discovery Program, Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 South Wood Street, Chicago, Illinois 60612, Department of Pharmacology, Georgetown University, 3900 Reservoir Road, NW, Washington, D.C. 20057, and Acenta Discovery Inc, 9030 S. Rita Road, Suite 300, Tucson, Arizona 85747 (At 2006-04-06)