In primary bone site, OS epigenetically downregulates CXCL12 expression by DNMT1, impairs cytotoxic T-cell homing to the tumor site and this chemokine gradient of CXCL12 drives the metastasis of OS cells to the lung (Figure 3, A), where CXCL12 is highly expressed. This evidence concerns the gene CXCL12 and neoplasm.