In a previous study, the activation of CXCR7 was found to improve the migration of colorectal cancer cells within the lung but not within the liver9, which may indicate that activating the CXCL12/CXCR7 axis in tumour cells could improve the secretion of CXCL12 and promote metastasis to lungs specifically10. The gene discussed is CXCL12; the disease is colorectal cancer.