PP2A represents an abundant class of structurally complex Ser/Thr phosphatases in mammalian cells, which maintains cell homoeostasis by counteracting most of the kinase-driven intracellular signaling pathways, have been shown to be genetically altered or functionally inactivated in many solid cancers and leukaemias, and is therefore a tumor suppressor [39], [40]. This evidence concerns the gene PTPA and leukemia.