SDC4 and neoplasm: The same intercellular communication signals were also observed in this study, where the CCL5 ligand secreted by BTG1+RGS1+ Tcm bound to SDC4/1 receptors on the surfaces of tumor cells, suggesting that the interaction between BTG1+RGS1+ Tcms and tumor cells via CCL5–SDC4/1 axis may promote tumor progression.