Tumor aggregates transmigrated across the endothelium under the stimulation of chemokine CXCL12, irreversibly damaging the endothelial integrity at the crossing site, while the transmigration was inhibited by blocking its CXCR4 receptor with AMD3100, highlighting the importance of the CXCL12-CXCR4 axis in cancer metastasis. The gene discussed is CXCL12; the disease is neoplasm.