Metformin, an AMPK agonist, is gradually emerging as a repurposed anticancer agent.20,21 A few clinical trials have also identified that metformin improves the progression-free survival and distant metastasis-free survival in lung cancer patients, but the underlying mechanisms remain elusive.22–24 We hypothesized that metformin treatment would inhibit lung cancer metastasis via AMPK activation. This evidence concerns the gene PRKAA1 and lung cancer.