PP2A is a major serine/threonine phosphatase that is implicated in the negative control of cell cycle progression. It is a trimeric holoenzyme that is comprised of a catalytic, structural, and regulatory subunit. PPP2R2B is a regulatory subunit of PP2A. The regulatory subunits of PP2A are grouped into 3 families: B/PR55, B’/PR61, and B’’/PR72. PPP2R2B encodes a beta isoform of the B/PR55 subunit family. PPP2R2B is brain specific. An expansion of a CAG repeat in the 5’region of PP2R2B is associated with spinocerebellar ataxia type 12 (SCA12), an autosomal dominant neurodegenerative disorder.