1. From the Department of Cell Differentiation, The Sakaguchi Laboratory, Department of Obstetrics and Gynecology, School of Medicine, Keio University, Tokyo, Japan; Biomedical Research Center and Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea; and Molecular/Cancer Biology Laboratory and Ludwig Institute for Cancer Research, Biomedicum Helsinki and Helsinki University Central Hospital, University of Helsinki, Helsinki, Finland.