Glucagon is a peptide hormone produced by the α-cells of the pancreatic Langerhans islets upon hypoglycaemia [9] and exerts its effects by binding to the glucagon receptor (GCGR), a G-protein coupled receptor (GPCR) expressed primarily in liver cells [10] and certain cancer cell types, including pancreatic neuroendocrine tumours (pNETs) [11]. This evidence concerns the gene GCGR and cancer.