DUSP1 and osteosarcoma: Mitogen-activated protein kinase (MAPK) phosphatase 1 (MKP-1), also known as dual specificity protein phosphatase 1 (DUSP1), is a nuclear mitogen and stress-inducible MKP that is highly expressed in different types of human tumors, including those of the lung, breast, bone, ovary, bladder, prostate, and osteosarcoma [5–8].