1. Department of Molecular Biology, Graduate School of Science, Nagoya University, and CREST, Japan Science and Technology Corporation, Chikusa-ku, Nagoya 464-8602
2. Division of Morphogenesis, Department of Developmental Biology, National Institute for Basic Biology, Okazaki 444
3. Pathology Division, National Cancer Center Research Institute, Chuo-ku, Tokyo 104-0045
4. Department of Microbiology and Molecular Genetics, College of Medicine, University of California, Irvine, California 92697-4025
5. Department of Molecular Cell Biology, Medical Research Institute, Tokyo Medical and Dental University, Chiyoda-ku, Tokyo 101-0062, Japan
6. Howard Hughes Medical Institute, Department of Pharmacology, and Center for Developmental Biology, University of Washington School of Medicine, Seattle, Washington 98195-7350