1. Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
2. Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
3. Laboratory of Molecular Pharmacology, NIH, Bethesda, MD 20892, USA.
4. Laboratory of Molecular Immunology, The Rockefeller University, Howard Hughes Medical Institute, New York, NY 10021, USA.
5. Mouse Cancer Genetics Program, NIH, Frederick, MD 20892, USA.
6. Genetics Department, National Cancer Institute, NIH, Bethesda, MD 20892, USA.
7. Department of Microbiology and Immunology, University of Maryland School of Medicine, 655 West Baltimore Street, BRB 13-01, Baltimore, MD 21201, USA.
8. Veterinary Resources Program, National Center for Research Resources, NIH, Bethesda, MD 20892, USA.
9. Molecular Cytology Core Facility and Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA.