CX3CR1 and brain neoplasm: In many CNS pathological conditions and animal disease models, a common phenomenon is the downregulation of core microglial genes: Tmem119, P2ry12, and Cx3cr1. While their expression is lower compared to homeostatic microglia, it is still at a sufficient level to discriminate microglia from bone marrow-derived monocytes and macrophages, which was shown in the brain tumor and EAE murine models [69,70,76].