ARG1 and central nervous system cancer: Consistent with the primary patient data (Figs. 2 and 4d–f), the expression of the glioma-derived IL-33 in vivo resulted in an increase in the abundance of arginase 1 (Arg1)-positive cells, indicative of a pro-tumorigenic macrophage population (Fig. 5a, b), while the Iba1+ cells in the absence of the nuclear localization (ΔNLS) did not express Arg1 implying that the macrophage recruited by glioma cells expressing this mutant have an M1 anti-tumorigenic phenotype that may mediate tumor cell clearance and regression of the ΔNLS tumors in vivo (Fig. 3c and Supplementary Fig. 3c).