1. Division of Gastroenterology and Hepatology, University of Michigan, Ann Arbor, Michigan, USA;
2. Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA;
3. Division of Gastroenterology and Hepatology, Indiana University, Indianapolis, Indiana, USA;
4. Section on Gastroenterology & Hepatology, Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina, USA;
5. Duke Clinical Research Institute, Durham, North Carolina, USA;
6. National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, USA.