Inactivates MAP kinases. Has a specificity for the ERK family . Plays an important role in alleviating chronic postoperative pain. Necessary for the normal dephosphorylation of the long-lasting phosphorylated forms of spinal MAPK1/3 and MAP kinase p38 induced by peripheral surgery, which drives the resolution of acute postoperative allodynia . Also important for dephosphorylation of MAPK1/3 in local wound tissue, which further contributes to resolution of acute pain . Promotes cell differentiation by regulating MAPK1/MAPK3 activity and regulating the expression of AP1 transcription factors .