VEGFA and neoplasm: Interestingly, tumor-derived factors such as granulocyte–macrophage colony-stimulating factor (GM-CSF), interleukin (IL) 3, and vascular endothelial growth factor (VEGF) are responsible for MDSC accumulation and expansion; while stromal- or activated T cells-derived factors such as IL-1β, IL-6, and prostaglandins are mostly responsible for MDSC activation26,28.