1. Department of Physiology and Biophysics, State University of New York at Buffalo, Buffalo, NY 14203, USA.
2. Department of Biochemistry, State University of New York at Buffalo, Buffalo, NY 14203, USA.
3. Department of Pathology and Laboratory Medicine, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
4. Gene Targeting and Transgenic Shared Resource, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.