{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Phosphatase and tensin homolog (PTEN) is a protein that, in humans, is encoded by the PTEN gene. Unlike most of the protein tyrosine phosphatases, this protein preferentially dephosphorylates phosphoinositide substrates. It negatively regulates intracellular levels of phosphatidylinositol-3,4,5-trisphosphate in cells and functions as a tumor suppressor by negatively regulating Akt/PKB signaling pathway. During tumor development, mutations and deletions of PTEN occur that inactivate its enzymatic activity leading to increased cell proliferation and reduced cell death."}]}]}