In a rat model of bronchopulmonary dysplasia (BPD), montelukast treatment inhibited the expression of hyperoxia-induced mesenchymal markers, such as collagen I (Col I), metalloproteinase-1 (MMP-1), MMP-3, TGF-β1, and Smad3, in lung tissues by inactivating the TGF-β1/Smad signaling pathway (Chen et al., 2020). Here, SMAD3 is linked to bronchopulmonary dysplasia.