CSF2 and neoplasm: Meanwhile, human RCC cells can directly secrete significant amount of GM-CSF [14], and recent studies have revealed an immunosuppressive effect of GM-CSF by expansion of myeloid-derived suppressor cells (MDSCs) and stimulation of FoxP3+ regulatory T cells (Tregs) in blood and tumor microenvironment, which leads to concerns about potential detrimental effects of this cytokine [15–17].