XRCC5 and lung cancer: Many studies have shown that miRNAs can function as oncogenes or tumor suppressors by post-transcriptionally inhibiting numerous target gene expressions in lung cancer.16 We successfully identified two miRNAs (hsa-miR-526b and hsa-miR-623) that could significantly inhibit Ku80 expression in A549 cells in our previous study.10 Our previous study had explored the function of hsa-miR-526b in NSCLC,10 so we chose to investigate the role of hsa-miR-623 in this paper.