1. Department of Molecular Pharmacology, National Cerebral and Cardiovascular Center Research Institute, Suita, Osaka 565-8565, Japan, Innovative Drug Research Laboratories, Kyowa Hakko Kirin Co., Ltd., Machida, Tokyo 194-8533, Japan, and Antibody Research Laboratories, Kyowa Hakko Kirin Co., Ltd., Machida, Tokyo 194-8533, Japan