1. Department of Experimental Pathology, Cancer Institute, Japanese Foundation for Cancer Research, 1-37-1 Kami-Ikebukuro, Toshima-ku, Tokyo 170-8455,1 and
2. Third Department of Internal Medicine, Nihon University School of Medicine, 30-1, Oyaguchi Kami-machi, Itabashi-ku, Tokyo 173-8610,2 Japan