Department of Tumor Biology, The Institute of Medical Science, The
University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639,
Japan; and Department of Integrated Biosciences,
Graduate School of Frontier Sciences, The University of Tokyo, 7-3-1
Hongo, Bunkyo-ku, Tokyo 113-0033, Japan (At 2000-10-10)
