IL6 and cancer: In the bone marrow, pro-cancer and pro-chronic inflammatory factors in TME have been proved to promote the expansion and differentiation of immature myeloid cell into MDSCs, including granulocyte monocyte colony stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating factor (M-CSF), S100 proteins, interleukin (IL)-6 and tumor necrosis factorα-alpha (TNF-α).