STK11 and familial pancreatic carcinoma: Because the TP53 tumor suppressor gene is frequently mutated in human pancreatic cancer (40%–70%)30 and LKB1 is down-regulated in around 20% of PDAC, we hypothesized that loss of Lkb1-mediated p53/p21 induction might be able to circumvent the need for p53 mutation in human PDAC and thus should not be down-regulated in those tumors with p53 mutation.