1. Department of Pediatrics, Hirosaki University Graduate School of Medicine, Hirosaki, Japan;
2. Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Bunkyo City, Tokyo, Japan;
3. Department of Pediatrics, Yokohama City University Graduate School of Medicine, Yokohama, Japan;
4. National Center for Child Health and Development Children's Cancer Center, Tokyo, Japan;
5. Department of Human Health Sciences,
6. Department of Pathology and Tumor Biology, Graduate School of Medicine, and
7. Institute for the Advanced Study of Human Biology (WPI ASHBi), Kyoto University, Kyoto, Japan;
8. Center for Hematology and Regenerative Medicine, Karolinska Institute, Stockholm, Sweden; and