Although lungs metastases were detected in both CXCR4+/+ and CXCR4+/− mice, tumor burden was significantly less in CXCR4+/− mice, Plerixafor treatment further reduced the size and number of lung metastases more effectively in CXCR4+/− mice, preserving the pulmonary architecture. The gene discussed is CXCR4; the disease is neoplasm.