PTEN dephosphorylates proteins and lipids such as AKT and phosphatidylinositol 3,4,5-trisphosphate -PIP3) and therefore functions as a key regulatory enzyme in a central signal transduction pathway. PTEN is expressed in almost all tissues of the body as a 403 amino acid protein with an estimated molecular weight of 47 kDa, however the actual migration observed on western blot may vary among distinct samples. PTEN interacts with many other proteins to regulate cell division and migration as well as promoting apoptosis when necessary. Mutation of PTEN results in many human cancers including melanoma and prostate carcinoma.