PP2A as a master regulator of the cell cycle.

Protein phosphatase 2A (PP2A) plays a critical multi-faceted role in the regulation of the cell cycle. It is known to dephosphorylate over 300 substrates involved in the cell cycle, regulating almost all major pathways and cell cycle checkpoints. PP2A is involved in such diverse processes by the formation of structurally distinct families of holoenzymes, which are regulated spatially and temporally by specific regulators. Here, we review the involvement of PP2A in the regulation of three cell signaling pathways: wnt, mTOR and MAP kinase, as well as the G1→S transition, DNA synthesis and mitotic initiation. These processes are all crucial for proper cell survival and proliferation and are often deregulated in cancer and other diseases.