AKT1 and cancer: In addition, lipid and protein phosphatases controlling Akt activity are frequently downregulated in human cancer determining the overexpression of phosphorylated Akt, such as inositol polyphosphate 4-phosphatase (INPP4), which catalyses the dephosphorylation of PI (3,4)P2 to PI(3)P at the plasma membrane and on endomembranes, leading, if it is reduced, to the subsequent increase of PI3K/Akt pathway activity [8,51].