Then, the tumor suppressor LKB1 is required to phosphorylate AMPK in response to biguanides.12 The following question could then be asked: if metformin action requires LKB1 to activate AMPK, and AMPK inhibits mTORC1, what are the consequences in terms of cancer incidence in patients treated with metformin for decades? Here, STK11 is linked to neoplasm.