ARG1 and glioma: In the case of GBs, glioma cells are able to stimulate GAMs to produce immunosuppressive molecules, such as IL-10, metalloproteinases (MMPs), chemokines as monocyte chemotactic protein-1 (CCL2), and ARG-1, that stimulate the tumor growth (Chang et al., 2016; Zhang I. et al., 2016; Gieryng et al., 2017b; Lisi et al., 2017).