1. Lineberger Comprehensive Cancer Center,1
2. Department of Pathology and Laboratory Medicine,2
3. Departments of Cell Biology and Anatomy and Pediatrics,3
4. Program in Molecular Biology and Biotechnology, 5 University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295, and
5. Laboratory of Biochemistry and Metabolism, 6 National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
6. Department of Biochemistry and Biophysics, 4 and