1. PDT Center, Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, New York 14263, Department of Dermatology, Roswell Park Cancer Institute, Buffalo, New York 14263, Department of Radiology, Washington University School of Medicine, St. Louis, Missouri 63110, Department of Chemistry, State University of New York, Buffalo, New York 14221, and Department of Biophysics, Anatomy Chemistry Building, University of Pennsylvania, Philadelphia, Pennsylvania