1. Department of Oral Pathology (A.Y.), Nagasaki University School of Dentistry, 1–7-1 Sakamoto, Nagasaki 852
2. Department of Molecular Medicine (T.K.), School of Medicine, Osaka University, 2–2 Yamada-oka, Suita, Osaka 565
3. “Form and Function”, PRESTO, Japan Science and Technology Corporation, and Department of Biochemistry (T.S.), School of Dentistry, Showa University, 1–5-8 Hatanodai, Shinagawa-ku, Tokyo 142, Japan