CCR2 and glioma: Studies have demonstrated that GAMs were recruited to sites of gliomas via interaction between CCL2/MCP-1 which are basically generated by glioma cells as well as its receptor CCR2 which is secreted by GAM and by a CCL7/MCP-3-CCR1/CCR2/CCR3-crosstalk (Figure 4) [98, 147–149].