CCR4 and glioblastoma: The distinguishing characteristics of macrophage populations A (cluster 3) and B (cluster 4) included higher expression of CD14 in cluster 3 and higher expression of the chemokine receptors CXCR3 and CCR4 in cluster 4 (Figure 2, B and C), verifying that these populations represent 2 activated, phenotypically distinct myeloid subsets in the C-GBM microenvironment.