GIPR and pancreatic insulinoma: Incretin receptors, including glucagon-like peptide-1 (GLP-1R) (35, 36) and glucose-dependent insulinotropic polypeptide receptor (GIPR) (37, 38), have been investigated with earnest in recent years, with putative utility in tumors such as insulinoma that often occur with low or absent expression of SSTR.