1. Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
2. Department of Molecular and Cellular Growth Biology, The VWhittier Institute for Diabetes and Endocrinology, La Jolla, CA 92037.
3. Department of Pathology, New York University School of Medicine, New York, NY 10016.
4. Department of Biochemistry, Cornell University Medical College, New York, NY 10021.