1. Contribution from the Department of Pharmacology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, New Jersey 08854-5635; the Department of Chemistry and Chemical Biology, Rutgers-The State University of New Jersey, 610 Taylor Road, Piscataway, New Jersey 08854-8087; and The Cancer Institute of New Jersey, New Brunswick, New Jersey 08901