Granulocyte colony-stimulating factor (G-CSF) [178,179], macrophage colony-stimulating factor (M-CSF) [178,179], GM-CSF [178,179], IL-6 [180], IL-1β [181], macrophage migration inhibitory factor (MIF) [182], polyunsaturated fatty acids, PGE2 [183,184], IL-17 [185], miRNAs derived from tumor exosomes (TEXs) [186,187], and vascular endothelial growth factor (VEGF) [188], which are produced by tumor cells or stromal cells in response to inflammation and chronic infection, are pivotal factors for the accumulation of MDSCs at tumor site. The gene discussed is CSF1; the disease is neoplasm.