STK11 and neoplasm: It works by targeting the enzyme AMP activated protein kinase (AMPK), which is regulated by a protein kinase known as Liver Kinase B1 (LKB1), and inducing muscles to take up glucose from the blood [5]. The LKB1 is a well recognized tumor suppressor and can be activated by exercise, suggesting that metformin might participate in suppressing tumorigenesis [6].