1. Department of Regenerative Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa 236-0004, Japan
2. Department of Cell Biology, Duke University School of Medicine, Durham, NC 27707, USA
3. Division of Regenerative Medicine, Center for Stem Cell Biology and Regenerative Medicine, Institute of Medical Science, University of Tokyo, Minato, Tokyo 108-8639, Japan
4. NODAI Genome Research Center, Tokyo University of Agriculture, Setagaya, Tokyo 156-8502, Japan
5. Department of Embryology, Nara Medical University, Kashihara, Nara 634-8521, Japan