1. Drug Development Laboratory, Department of Pharmacology, Toxicology & Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas 66160-7419, Laboratory of Preclinical Pharmacology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, Department of Medicine, The University of Miami School of Medicine, Miami, Florida 33136, and Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-5635