MMP9 and lung adenocarcinoma: Overexpression of GPX2 in A549 cells revealed a significant increase in the expression levels of MMP2 and MMP9 in the cells, while the inhibition of GPX2 expression significantly decreased the expression levels of MMP2 and MMP9 in A549 cells, tentatively confirming that the effect of GPX2 on invasive metastasis of lung adenocarcinoma A549 cells was associated with reduced secretion of MMPs.