CCL8 and glioblastoma: The TAMs also play a role in GBM invasion through the expression of CCL8 and the activation of signaling pathways in GBM cells through the binding of CCL8 to CCR1 and CCR5 receptors [208], the secretion of CSF-1 [209] and epidermal growth factor (EGF) by GBM and microglia, respectively, have also been shown to stimulate GBM invasion through the recruitment of TAMs and activation of signaling pathways in GBM cells through the binding of EGF to epidermal growth factor receptors (EGFR) [210].