The ability of the incretins to promote cAMP production has been demonstrated in various cell lines, including rat insulinoma RIN1046-38 cells [78], isolated rat islets [48,636], hamster pancreatic In111 cells [637], hamster β-cell HIT-T15 cells [616], and mouse insulinoma βTC-3 cells [168]. Here, GCG is linked to pancreatic insulinoma.