Regulates mitogenic signal transduction by dephosphorylating both Thr and Tyr residues on MAP kinases ERK1 and ERK2. H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Hollow spherical complex composed of 24 subunits with pseudooctahedral symmetry, has a tetramer as the basic unit. Expressed at moderate levels in nearly all tissues and cells including brain, spleen, and testes with the higher expression in the heart and lung and lower expression in skeletal muscle and kidney. Undetectable in liver. Expressed in many areas of the brain with very strong expression in the hippocampus, piriform cortex, and the suprachiasmatic nucleus. By mitogens and by stress. Phosphorylation in the C-terminus by ERK1/2 inhibits proteasomal degradation and stabilizes the protein. Belongs to the protein-tyrosine phosphatase family. Non-receptor class dual specificity subfamily.