While microglial activation is reported after irradiation in both juvenile and adult rodent brain (74, 112) intriguingly, we observed trivial Iba1+ cells in the radiation control, indicating a possible clearance of the activated microglia over time, as the brain samples were harvested 58 days post-IR, at a time-point close to moribund for tumor-bearing mice groups. This evidence concerns the gene AIF1 and neoplasm.