MMP9 and lung cancer: Additionally, the microfluidic lung-BBB-brain model recapitulates lung cancer metastasis to the brain via the BBB system, indicating that tumor cell expression of Aldoketo reductase family 1 B10 (AKR1B10) is tightly linked to BBB extravasation across the BBB, resulting in the upregulation of MMP2 and MMP9, and altering the ECM, which may facilitate inflammation [154] [Fig. 3F].