In a murine glioma model where Csf1 expression is increased approximately 2.5-fold compared to normal brain, CSF1R inhibitors decrease expression of M2 markers including Arg1 in GAMs [17, 18], suggesting that increased CSF1/CSF1R signaling can promote polarization toward a M2 phenotype in the diseased CNS. Here, ARG1 is linked to glioma.