Wang et al. first found that EZH2 inhibitor-treated BC cells, including 4T1 and MDB-MB-231 cells, enhanced M2 macrophage polarization in vitro and the tumor infiltration of M2 macrophages and BC cell lung metastasis in vivo, whereas EZH2 knockdown showed the opposite effects. The gene discussed is EZH2; the disease is neoplasm.