CD80 and cancer: Previous literatures describe that M2-polarized macrophages also contribute to drug resistance [21, 22], and we verified that CD206 was significantly upregulated, and CD80 was downregulated in the cancer tissues collected form recurrent GBM patients suffered from TMZ treatment, in contrast with the patients without TMZ treatment (Figures 1(i) and 1(j)), which supported the notion that enrichment of M2 macrophages was relevant to TMZ resistance in GBM.