Comparing the transcriptomes of contralateral GBM microglia with those of normal brain microglia showed that microglia located far from the GBM tumor bed are activated significantly, upregulating genes involved in major histocompatibility complex II (MHCII) antigen processing and presentation, cellular responses to interferon (IFN)-β,γ and innate immune response, whereas the top gene signatures of normal brain microglia related to phagocytosis, and positive regulation of NF-KB transcription (Fig. 3h and Extended Data Fig. 4i). Here, IFNB1 is linked to glioblastoma.