STK11 and cancer: Liver kinase B1 (LKB1), also known as STK11, is a serine–threonine kinase whose mutation is responsible for Peutz–Jeghers Syndrome, which is a hereditary condition that results in the development of benign (hamartomatous) polyps in the gastrointestinal tract, mucocutaneous pigmentation, and a predisposition to developing cancers in a variety of tissues: the colon, small intestine, breast, ovary, pancreas, and lung [12,13,14,15,16].