LKB1 was originally identified as a tumor suppressor gene located on human chromosome 19p13 and it is responsible for Peutz-Jeghers syndrome, an autosomal dominant inherited disorder characterized by hamartomatous polyps and mucocutaneous pigmentation (177, 178) and also an increased risk for various malignancies including gastrointestinal, gynecological, colorectal, pancreatic, and lung cancers (179–181). The gene discussed is STK11; the disease is lung cancer.