1. Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794−3400, Institute of Chemical Biology & Drug Discovery, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461, and Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Elm and Carlton Streets, Buffalo, New York 14263