CSF2 and cancer: Cancer cells, activated T cells and tumor-associated stromal cells express cytokines such as VEGF, TGF-β, and PGE2, granulocyte-macrophage colony-stimulating factor (GM-CSF) and TNFα, which might cooperatively disrupt myeloid cell maturation, promote the differentiation toward MDSCs, and enhancing MDSCs activation in the TME (Safarzadeh et al., 2018).