In fact, the GBM-associated microglial cells and macrophages (GAMMs), were reported to show not only classical macrophage activation aspects, but also typical hints of an alternative macrophage activation, the latter possibly involving inhibition of inflammation via production of TGFβ1, arginase 1 and interleukin 10, shaping the tumor micro-environment through vascular endothelial growth factor (VEGF) and matrix metalloproteases (MP). Here, ARG1 is linked to glioblastoma.