STK11 and cancer: And such K6 linkage primed LKB1 kinase activity contributed to its tumor suppressive, but not promoting function in NSCLC, this is consistent with previous finding that LKB1 functions as a tumor suppressor in NSCLC and other cancers such as sporadic endometrial cancers,38 neuroendocrine lung cancers,39 pancreatic and biliary neoplasms.40 The seemingly contradictory roles of K63- and K6-linkages on LKB1 function in cancer malignancy may be explained by the differential tumor models.