MMP9 and lung cancer: Figure 3 shows that in the si-Nrf2 group, the proliferation activity, migration number, and protein levels of Nrf2, HO-1, MMP-9, and MMP-2 of lung cancer cells decreased, while the expression levels of Cleaved Caspase-3 and Cleaved Caspase-9 and the apoptosis rate raised (P < 0.05).