CXCL12 and central nervous system cancer: The ELISA results showed that FTY720 did not affect CXCL12 secretion by glioma cells (Figure 2E), indicating that FTY720 could regulate CXCL12–CXCR4 cross-talk between microglia and glioma via decreasing the expressions of CXCR4 on the microglia.