CXCR4 and small cell lung carcinoma: In the ATC subgroup, a strong trend for an association between the protein and mRNA levels was noticed (n=17, r=0.472, p=0.056) and, finally, in the SCLC subgroup a significant correlation between the CXCR4 protein and mRNA levels could be detected (n=17, r=0.510, p=0.037).