The tumor suppressor gene STK11 encoding Serine/Threonine Kinase 11 (STK11) is associated with Peutz-Jeghers Syndrome (PJS), a heritable gastrointestinal disease that increases lifetime cancer risk, and with somatic variation that contributes to ~30% of lung and 20% of cervical cancers. This evidence concerns the gene STK11 and Peutz-Jeghers syndrome.