Human secretin receptor (gene name SCTR) is a G-protein-coupled receptor, a member of the class B GPCR subfamily. Secretin receptor binds to peptide secretin and the pituitary adenylate cyclase activating peptide. It was the first receptor that was cloned in the class B family of GPCRs. Secretin receptor is also regulated by peptide hormones from the glucagon hormone family. The receptor activates two distinct intracellular signaling pathways, i.e. the adenyl cyclase and the phosphatidyl-inositol calcium pathways. Northern blot analysis has shown that the secretin receptor is expressed in pancreas, kidney, small intestine, lung, liver, and in trace levels in the brain, heart and ovary. Secretin-receptor mRNA is abundant in all gastrinomas, enriched in one specific variant. Knockout of secretin receptor was shown to reduce large cholangiocyte hyperplasia. Studies have also demonstrated the potential use of secretin as a therapy for ductopenic liver diseases.