MMP9 and non-small cell lung carcinoma: The results of these indicators in our study not only helped us to confirm that the circDENND4C/miR-200b/MMP-9 regulatory network existed in NSCLC, but also might indicate that knockdown of circDENND4C halted or possibly reversed NSCLC growth and metastasis by inhibiting MMP-9 with releasing miR-200b.