CD274 and neoplasm: For example, upon the high levels of tumor-derived lactate, high-expressed PD-L1 on the surface of tumor cells, or IL-4, IL-10, and TGF-β are present in TME, tumor-associated macrophages (TAMs) would polarize into the M2 phenotype, which plays a pro-tumor role (Goossens et al., 2019; Petty et al., 2019).