A previous study by Yi et al. has further reported that GSCs are better at recruiting microglia than glioma cells as GSCs expressed more Chemokine (C-C motif) ligand 2 (CCL2), Chemokine (C-C motif) ligand 5 (CCL5), Chemokine (C-C motif) ligand 7 (CCL7), Vascular endothelial growth factor A (VEGF-A) and neurotensin (NTS) than glioma cells that infiltrate the brain tissue [12]. This evidence concerns the gene CCL7 and central nervous system cancer.