1. Department of Biochemistry and Integrative Medical Biology, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan, and The Institute of Physical and Chemical Research (RIKEN), RIKEN Harima Institute, 1-1-1 Kouto, Mikazuki-cho, Sayo, Hyogo 679-5148, Japan