Another member of the energy/nutrient-sensing pathway is the kinase LKB1, encoded for by STK11. Mutations in STK11 predispose to the Peutz-Jeghers tumor syndrome (PJS) that features benign gastrointestinal (GI) polyps as well as malignant tumors in the GI, breast and gynecological organs. This evidence concerns the gene STK11 and Peutz-Jeghers syndrome.