1. Department of Environmental and Occupational Health, Department of Pharmaceutical Sciences, and the University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15238, Laboratory of Molecular Pharmacology, Developmental Therapeutics Program, Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, and Division of Biomedical Marine Research, Harbor Branch Oceanographic Institution, Inc., Fort Pierce, Florida 34946