Protein phosphatase 2C alpha, also called PP2Calpha, Protein Phosphatase, Magnesium-dependent type 1A, and PPM1A, dephosphorylates proteins with some preference for phospho-threonine over phospho-serine residues 1. It is insensitive to the PP1 and PP2a inhibitors such as okadaic acid 2, but has an absolute requirement for either magnesium or manganese ions 3 and can be activated by unsaturated fatty acids such as arachidonic and oleic acids 4 . Overexpression of PP2Calpha causes G2/M cell cycle arrest and apoptosis that has been associated with the activation of p53 5 . Dephosphorylation of proteins in the nucleus by PP2Calpha is suspected to play a role in terminating or reducing the sensitivity of the responses to SMADS 6 and stress-activated proteins such as p38 and JNK 7.