The FDA has approved human synthetic secretin for (!)the stimulation of pancreatic secretions containing bicarbonate, (2) aiding the diagnosis of pancreatic exocrine dysfunction, (3) the use of gastrin secretions to assist in the diagnosis of gastrinoma, and (4) the stimulation of pancreatic secretions to help identify the ampulla of Vater and accessory papilla during ERCP. This evidence concerns the gene GAST and gastrin-producing neuroendocrine tumor.