This was partly attributable to transcriptional activation, because our previous study demonstrated that Sp1 directly bound to the DDX39B promoter and induced its transcription in colorectal cancer (CRC) cells.38 Here, we reported that the protein expression of DDX39B, but not its mRNA expression, was notably increased in brain metastatic tissues of NSCLC patients compared with patient-matched primary tumors, suggesting a post-translational regulation of DDX39B during metastasis process. This evidence concerns the gene SP1 and non-small cell lung carcinoma.