The increased number of MDSCs in tumor-bearing hosts is commonly attributed to aberrant bone marrow myelopoiesis triggered by tumor-derived growth factors such as G-CSF, IL-6, GM-CSF, IL-1β, prostaglandin E2 (PGE2), tumor necrosis factor α (TNFα) and vascular endothelial growth factor (VEGF)48,55,56. Here, TNF is linked to neoplasm.