Members of the protein phosphatase 2C (PP2C) family of isoenzymes are serine/threonine protein phosphatases that act as monomers, are magnesium or manganese dependent, and are structurally distinct from PP1, PP2A, and PP2B protein phosphatases. There are 14 mammalian PP2C genes that encode for members of the PP2C family of isoenzymes. Members of this family include PP2C alpha (PPM1A), PP2C beta (PPM1B), PP2C gamma (PPM1G), and PP2C delta (PPM1D). PPM1B represents the protein phosphatase 2C (PP2C) beta isoform 1. Six splice variants of the PPM1B have been identified PPM1B activation by lipophilic compounds has been demonstrated to be associated with the induction of apoptosis PPM1B activity has been shown to be involved in cell cycle control and the dephosphorylation of cyclin dependent kinases cdk2 and cdk6.