The tumor microenvironment likely plays a significant role on a case or disease-specific basis, as the relative presence of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GBM-CSF) influences the development of gMDSCs or mMDSCs, respectively (104, 107, 108). This evidence concerns the gene CSF2 and neoplasm.