PTEN can be frequently lost in melanoma,64 where it functions as a tumor suppressor to negatively regulate PI3K-AKT signaling through the dephosphorylation of the plasma membrane bound phospholipid, phosphatidylinositol-3,4,5-trisphosphate, which functions downstream of PI3K to activate AKT. The gene discussed is AKT1; the disease is melanoma.