Cerulein is an analog of cholecystokinin that causes bile reflux into the pancreatic duct and thus pancreatitis by causing loosening of the Oddi sphincter and contractions of the gallbladder.5 Cerulein has been used in experimental pancreatitis models with intraperitoneal, intravenous, and subcutaneous administration.6 The gene discussed is CCK; the disease is pancreatitis.