The LKB1-AMPK pathway-friend or foe in cancer?

Use of the biguanide metformin, an AMPK activator, is associated with a reduced incidence of cancer in diabetics, but it has been unclear whether this requires AMPK. In this issue of Cancer Cell, Shackelford and colleagues show, paradoxically, that biguanides are more effective in the treatment of mouse tumors that lack a functional LKB1-AMPK pathway.