Dual specificity phosphatase 18, also known as DUSP18, is a member of the dual-specificity phosphatase (DSP) family, which catalyzes dephosphorylation of phosphotyrosine and phosphothreonine residues. DUSP18 is inhibited by iodoarectic acid and is activated by manganese ions. Along with having preferential enzymatic activity against phosphorylated tyrosine residues over threonine residues, DUSP18 also dephosphorylates p-nitrophenyl phosphate (pNPP) in vitro. This protein is widely expressed with highest levels in liver, brain, ovary and testis. Recombinant human DUSP18 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.