1. Department of Molecular Biology, Department of Surgery, and Department of Neurosurgery, Graduate School of Medical Science, Kyushu University, Fukuoka 812-82, Japan; Laboratory of Cellular and Molecular Biology, The Institute of Physical and Chemical Research (RIKEN) 2-1 Hirosawa, Wako, Saitama 351-01, Japan; Inheritance and Variation Group, PRESTO, Japan Science and Technology Corporation, Kyoto