Our work also demonstrated that CCL2 is robustly increased in high-grade canine astrocytoma compared to normal brains [16] and given the role of CCL2 and CCR4 in both human and mouse models of gliomas, we studied here how this increased expression of CCL2 may affect the canine Tregs and CD4+ helper T-cells. Here, CCR4 is linked to central nervous system cancer.