1. The Cancer Institute, Japanese Foundation for Cancer Research, 1 and
2. PRESTO, Japan Science and Technology Corporation, 2 Toshima-ku, Tokyo 170-8455, and
3. Department of Molecular Biology, Tottori University School of Medicine, Yonago, Tottori 683-0826, 3 Japan;
4. Department of Genetics, Cell Biology and Development, University of Minnesota Cancer Center, Minneapolis, Minnesota 55455 4 ; and
5. Mammalian Genetics Laboratory, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, Maryland 217025