1. Biophysics Graduate Group, University of California, Berkeley, California 94729
2. Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, California 92093
3. Department of Molecular and Cell Biology, University of California, Berkeley, California 94729
4. Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio 44106
5. Department of Pharmacology, Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106