CCL2 and glioblastoma: Before performing specific studies, we verified that the cultured cells were negative for CD31 and CD45 surface markers and positive for CD44 and CD73 surface markers (Fig. 2g).To study the role of chemokine receptors in MSC migration toward CD133+ GBM cells, we examined the expression of homing markers (the receptors for MCP-1/CCL2 and SDF-1/CXCL12, respectively) in MSCs, which co-expressed CXCR4 and CCR2 (95.9%) (Fig. 2g) by FACS analysis.