1. Department of Cell Biology, Faculty of Medicine, Kyoto University, Sakyo-ku, Kyoto 606, Japan; Department of Molecular Cell Biology, Institute of DNA Medicine, The Jikei University School of Medicine, Nishi-Shinbashi, Minato-ku, Tokyo 105, Japan; Laboratory of Cell Biology, Kan Research Institute Inc., Minami-Kaneda, Suita, Osaka 564, Japan; and Department of Anatomy, Faculty of Medicine, Kyoto U