CX3CR1 and glioblastoma: The previously reported markers were also compared among different tumor types, for example, the homeostasis myeloid subpopulation with high expression levels of P2RY12 and CX3CR1 in gliomas and cluster 2 marked with the pathway of “GTPase signal transduction” in ependymoma (9), the activated microglial subsets highly expressing CD83 and TNF in GBM, and the clusters6 marked with pathways of “positive cytokine production” in ependymoma (23) (Figure 4C).