PPP2R5C is one of the members of regulatory subunits of protein phosphatase 2A (PP2A), which plays a critical role in cell proliferation, differentiation and transformation, based on its induction of dephosphorylation of P53 at various residues. Recently, it was characterized that the alteration of expression pattern of PPP2R5C is associated with cell malignant transformation, thus PPP2R5C was thought as a marker for progressive disease in B-CLL. In this article the gene structure and biological function of PPP2R5C as well as relation of PPP2R5C with genesis and development of cancer were discussed.