1. The Research Institute of the McGill University Health Centre and the Department of Medicine, McGill University, 1001 Decarie Boulevard, Montreal, Quebec, Canada
2. Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, sponsored by the National Cancer Institute, 8560 Progress Drive, Frederick, Maryland
3. Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, 1985 Zonal Ave, Los Angeles, California