Fig. 1

Macrophage polarization and its function in cancer progression. After differentiation into macrophages from monocytes, macrophages can be further polarized into M1 and M2 subsets under different stimuli or microenvironments. M1 macrophages inhibit tumourigenesis by secreting IL-1β, IL-18, IFN-γ, and TNF-α, whereas M2 macrophages promote cancer development through several biological molecules, such as Arg1, IL-4, and TGF-β