1. Department of Gastroenterology and Hepatology, Chuo-ku, Sapporo, Japan
2. Department of Surgery, Surgical Oncology and Science, Chuo-ku, Sapporo, Japan
3. Department of Surgical Pathology, Sapporo Medical University School of Medicine, Chuo-ku, Sapporo, Japan
4. Department of Gastroenterology, Muroran City General Hospital, Sapporo, Japan
5. Department of Molecular Biology, Sapporo Medical University School of Medicine, Sapporo, Japan