We found that metformin during normal glucose conditions significantly reduced proliferation and promoted apoptosis through PARP cleavage in pancreatic cancer cells with functional LKB1 (MIAPaCa-2, BxPC-3 and PANC-1), while being incapable of suppressing growth under the same conditions in AsPC-1 pancreatic cancer cells. Here, STK11 is linked to familial pancreatic carcinoma.