1. Department of Gene Regulation1 and
2. Tsukuba Research Laboratories, Eisai Co., Ltd., Tsukuba-shi, Ibaraki 300-26,2 Japan;
3. Laboratory of Molecular Genetics,3 Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108, and
4. CGMC, CNRS UMR106, Universite Claude Bernard Lyon-1, 69622 Villeurbanne Cedex, France4; and
5. Institute of Cancer Research, Chester Beatty Laboratories, London SW3 6JB, United Kingdom5