MMP9 and non-small cell lung carcinoma: In this study, consistent with previous studies, it was found that circDENND4C and MMP-9 were significantly upregulated in all NSCLC cell lines, but miR-200b was markedly downregulated in some NSCLC cell lines, in comparison with the normal HBE cells, which suggested that the abnormal expression of circDENND4C, miR-200b, and MMP-9 might be closely correlated with the progression of lung cancer, and may be a potential biomarker and therapeutic target for NSCLC.