GIP (Gastric Inhibitory polypeptide ) belongs to the glucagon superfamily. The encoded protein is important in maintaining glucose homeostasis as it is a potent stimulator of insulin secretion from pancreatic beta-cells following food ingestion and nutrient absorption. This gene stimulates insulin secretion via its G protein-coupled receptor activation of adenylyl cyclase and other signal transduction pathways. It is a relatively poor inhibitor of gastric acid secretion. Mature GIP is a highly conserved 42 amino acid polypeptide belonging to the glucagon family. GIP is highly expressed as a pre-pro-protein in the duodenum and the jejunum. The mature secreted polypeptide acts as a potent stimulator of insulin secretion and a poor inhibitor of gastric acid secretion.