Institute of Molecular and Cellular Biosciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-0032, Janssen-Kyowa CO. Ltd., Takanawadai Daiichi-Seimei Bldg, Higashi-Gotanda, Shinagawa-ku, Tokyo 141, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Kami-Ikebukuro, Toshima-ku, Tokyo 170, Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113−0033, and Department of Microbiology, University of Virginia,... (At 2000-03-01)