1Institute of Basic Medical Sciences and Center for Tsukuba, Advanced Research Alliance, University of Tsukuba, Tennoudai, Tsukuba 305, Japan
2Department of Molecular Genetics, National Institute of Neuroscience, Ogawa-higashi, Kodaira 187, Japan
3Precursory Research for Embryonic Science and Technology, Japan Science and Technology, Kawaguchi, Saitama, 332, Japan
4Department of Biochemistry, Tohoku University School of Medicine, Seiryo-machi, Aoba-ku, Sendai, 980-77, Japan
5Department of Biochemistry, Hirosaki University School of Medicine, Zaifu-cho, Hirosaki, 036, Japan
6Institute for Molecular and Cellular Biology, Yamadaoka 1-3, Suita, 565, Japan