1. Cancer Research U.K. Experimental Cancer Chemotherapy Research Group, Centre for Biomolecular Sciences, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, U.K., Chemistry Department, The Open University, Walton Hall, Milton Keynes MK7 6AA, U.K., Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, and Laboratoire de Biophysique, INSERM U565, CNRS UMR5153, Museum National d’Histoire Naturelle, 43 Rue Cuvier, 75005 Paris, France