– Human DUSP3 belongs to the dual specificity protein phosphatase subfamily. DUSPs are a heterogeneous group of protein phosphatases that can dephosphorylate both phosphotyrosine and phosphoserine/phosphothreonine residues within the one substrate. These phosphatases inactivate their target kinases by dephosphorylating both the phosphoserine/threonine and phosphotyrosine residues. DUSPs are major modulators of critical signalling pathways that are dysregulated in various diseases. They negatively regulate members of the mitogen-activated protein kinase superfamily, which are associated with cellular proliferation and differentiation. DUSP3 is expressed in human tissues including breast and ovarian.DUSP3 shows activity both for tyrosine-protein phosphate and serine-protein phosphate, but displays a strong preference toward phosphotyrosines. Human DUSP3 specifically dephosphorylates and inactivates ERK1 and ERK2.