1. Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD
2. Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD
3. Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD
4. Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD
5. Department of Medicine and Scott & White Digestive Disease Research Center, Texas A&M Health Science Center, College of Medicine, and Scott & White Hospital, and Research Service, Central Texas Veterans Health Care System, Temple, TX
6. Division of Gastroenterology and Hepatology, Mayo Clinic School of Medicine, Rochester, MN