CXCR4 and non-small cell lung carcinoma: In the group of patients with brain-specific metastasis, CXCR4 overexpression was observed in 31 samples of NSCLC tissue (91.2%), whereas of the 34 patients without metastases, CXCR4 overexpression was observed in five samples of NSCLC tissue (14.7%), which was significantly lower compared with that of patients with brain-specific metastasis according to the χ2 tests (P<0.001; Table III).