STK11 and cancer: The exploitation of energetic reactions to cellular stress has been shown to be a significant vulnerability of LKB1-deficient tumors [48]. In the presence of LKB1, normal cells will activate AMPK causing restricted growth and prolonged survival. However, tumors which lack LKB1 are very sensitive to apoptosis as they have an inability to restore their ATP levels [48]. These findings led to several retrospective analyses suggesting a correlation between oral biguanide, metformin, and reduced cancer risk [49-52].