AIF1 and neoplasm: On the other hand, tumor implanted mice that received RT + aPD-1 treatment showed 1.6-fold increase in the number of Iba-1 positive cells per 40X magnification field in the subcortical white matter compared to sham mice, suggesting activation of microglia or macrophages by the combined treatment (Fig. 2A,C, P < 0.05).