CSF2 and neoplasm: To begin, tumor cells induce MDSCs generation and recruitment via the secretion of stem cell factor (SCF), granulocyte macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), vascular endothelial growth factor (VEGF), and macrophage colony-stimulating factor (MCSF) [82,83,84].