CSF1 and neoplasm: M1 macrophages are activated by interferon-γ (IFN-γ), tumor necrosis factor (TNF) and lipopolysaccharide (LPS), among others, and exhibit significant tumor-killing and phagocytic effects 4, 5, while M2 TAMs can be stimulated by transforming growth factor (TGF), interleukin 4 (IL4) and macrophage colony-stimulating factor (M-CSF) et al., and often promote tumor cell growth and exhibit an immunosuppressive phenotype 6, 7.