1. Department of Gastroenterology, Asan Digestive Disease Research Institute, Seoul, Korea
2. Department of Pharmacology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
3. Department of Pathology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea
4. Department of Colon and Rectal Surgery, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea