Next, to explore the function of SerpinB2 in M1/M2 macrophage polarization and tumor cell proliferation and migration, SerpinB2 siRNA-transfected RAW264.7 (RAW264.7-siSB2) or wild-type RAW264.7 cells (RAW264.7 WT) were co-cultured with MDA-MB-231 cells. This evidence concerns the gene SERPINB2 and neoplasm.