CCR2 and central nervous system cancer: Interestingly, while Ccr2/CCR2 is dramatically downregulated upon entry into the parenchyma and during the monocyte-to-macrophage transition in glioma (55), and also BrM (27), Cx3cr1/CX3CR1 levels are upregulated in TAM-MDMs (Table 2), whereas the protein was downregulated on the majority of MDM subsets but remained abundant on only a small subset (27).