Several types of induction can contribute to the accumulation of MDSCs, including induction by inflammatory cytokines and growth factors (such as granulocyte-macrophage colony stimulating factor (GM-CSF) [20, 21] and interleukin (IL)-6 [22]) and tumor-derived factors (such as vascular endothelial growth factor (VEGF) [23] and transforming growth factor (TGF)-β1 [24]). This evidence concerns the gene CSF2 and neoplasm.