1. Laboratory of Cell Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma 371-8510, Japan.
2. Supermolecular Science Division, Electrotechnical Laboratory, Tsukuba, Ibaraki 305-8568, Japan.
3. Department of Physiology, Nagoya University School of Medicine, Nagoya, Aichi 466-8550, Japan.
4. Department of Biology, Tokyo Gakugei University, Koganei, Tokyo 184-8501, Japan