STK11 and cancer: Higher AMPK expression has been found to correlate with lower tumor grade and/or grade in various cancers, including ovarian, hepatocellular, pancreatic, breast, and gallbladder cancers [28, 29], and evidence indicates that the tumors in Peutz-Jeghers syndrome may result from deficient activation of AMPK due to inactivation of serine/threonine kinase 11, the major upstream kinase required for AMPK activation [30].