1. Bioscience Center, Nagoya University, Furo‐cho, Chikusa‐ku, Nagoya 464‐01, Japan,
2. Mitsubishi‐Kasei Institute of Life Science, Minamiooya 11, Machida‐shi, Tokyo 194, Japan,
3. Research Institute for Disease Mechanism and Control, School of Medicine, Nagoya University, Tsurumai‐cho 65, Showa‐ku, Nagoya 466, Japan,
4. Fujita Health University Institute for Comprehensive Medical Science, Kutsukake‐cho, Toyoake, Aichi 470‐11, Japan