BAX and bronchopulmonary dysplasia: In order to further verify the close relationship between CDK5 and BPD‐related hippocampal injury, we not only detected the expression of cleaved caspase‐3, Bax, and Bcl‐2 by western blot after ROS treatment, but also observed the main apoptotic regions and measured the apoptosis ratio of the hippocampus of BPD mice by TUNEL staining.