MDSCs are induced by tumor-mediated inflammation [16–18], recruited to the circulation via tumor-derived factors such as IL-1, IL-6, GM-CSF, G-CSF, and VEGF [19–21], and accumulate in the tumor, tumor-draining lymph node (LN), and spleen, with MDSC numbers increasing with tumor load [16, 21]. The gene discussed is CSF2; the disease is neoplasm.