1. Division of Integrative Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan.
2. Division of Stem Cell Regulation, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan.
3. Graduate School of Sciences, The University of Tokyo, Tokyo 113-8654,Japan.
4. Research Center for Advanced Science and Technology, The University of Tokyo,Tokyo 153-8904, Japan.
5. Laboratory of Gene Expression and Regulation, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan.
6. PRESTO, JST, Saitama 332-0012, Japan.