In our previous study on fetal human lung fibroblasts, we showed that ACE-2 is significantly decreased by hyperoxic gas lung injury due to ACE-2 enzyme shedding mediated by TACE/ADAM17.8 Due to the important role of the alveolar epithelia development in hyperoxic lung injury and BPD, we decided to investigate the effects of hyperoxia on ACE-2 in AECs using the human lung alveolar epithelial cell line A549 as a cell culture model. The gene discussed is ADAM17; the disease is bronchopulmonary dysplasia.