1. Division of Gastroenterology, Faculty of Medicine; University of Tsukuba; Tsukuba; Ibaraki; Japan
2. Graduate Institute of Medicine, Kaohsiung Medical University; Kaohsiung; Taiwan
3. Division of Gene Engineering; RIKEN BioResource Center; Tsukuba; Ibaraki; Japan
4. Laboratory of Oncology; Department of Life Science; Tokyo University of Pharmacy and Life Sciences; Hachioji; Tokyo; Japan