To characterize the function of CXCR4 silencing in a lung adenocarcinoma cell line, functional assays revealed that CXCR4 silencing could effectively inhibit the tumorigenic phenotype by reducing frequencies of colony formation in soft agar compared with cells treated with scramble shRNAs (P < 0.001) (Fig. 1A and Fig. S3A). Here, CXCR4 is linked to lung adenocarcinoma.