1. Institute of Clinical Molecular Biology and Central Laboratory, Peking University, People's Hospital, Beijing 100044, P.R.�China
2. Department of Gastroenterology, Peking University, People's Hospital, Beijing 100044, P.R. China
3. Institute of Clinical Molecular Biology and Central Laboratory, Peking University, People's Hospital, Beijing 100044, P.R. China
4. Department of Pathology, Peking University, People's Hospital, Beijing 100044, P.R. China