1. *Center for Priority Areas, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan;
2. Department of Chemistry, Graduate School of Sciences and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan;
3. Innovative Drug Research Laboratories, Kyowa Hakko Kirin Co., Ltd., Takasaki, Gumma, 370-1295, Japan; and
4. Department of Molecular Genetics, National Institute of Genetics and The Graduate University for Advanced Studies, Mishima, Shizuoka 411-8540, Japan