GCG and cancer: In addition to SSTR-2 and SSTR subtypes (SSTR-3 and SSTR-5), other regulatory peptide receptors such as incretin receptor glucagon-like peptide 1 (GLP-1) and cholecystokinin receptor family (CCK-1 and CCK-2 subtypes), glucose-dependent insulinotropic polypeptide receptor (GIP) and gastrin-releasing peptide receptors are overexpressed in several human cancers [76].