NOS2 and cancer: MDSCs accumulate aberrantly in cancers, diverting myeloid progenitors away from their normal differentiation pathway to dendritic cells, macrophages and granulocytes, towards a pathological state, suppressing CD8+ T cell function by the production of reactive oxygen species, and expression of the enzymes ARG1 and inducible nitric oxide synthase (iNOS) [108, 109] and promoting metastasis and osteolysis [107].