1. From the Department of Immunology, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan; Department of Immunology and Cell Biology, Graduate School of Biostudies, Kyoto University, Kyoto, Japan; Laboratory for Lymphocyte Development, RIKEN Research Center for Allergy and Immunology, Yokohama, Japan; and Division of Cell Regeneration and Transplantation, Advanced Medical Research Center, Nihon University School of Medicine, Tokyo, Japan.