The aim of the present study was to produce the human dual specificity phosphatase 1 (DUSP1) protein with biological activity and to investigate its in vitro effects on cancer cells. DUSP1 protein was expressed in the baculovirus expression system and purified by Ni-Affinity chromatography followed by dialysis in PBS. The purified protein was verified by SDS-PAGE and western blot analysis. Six cancer cell lines were then cultured in the presence of DUSP1 for various periods of time, and the phosphorylated extracellular signal-regulated kinase (...