MiR-21 in exosomes or extracellular vesicles induced by GBM tumor cells can be incepted by GAMs and upregulate IL-6, TGF-β, and Arg-1 in M2 GAMs (103, 104), resulting in downregulating the immune response and accelerating growth and invasion of GBM tumor cells (103). This evidence concerns the gene ARG1 and glioblastoma.