MKI67 and bronchopulmonary dysplasia: Given the known role of PI3K/Akt/mTOR/Ki67 signaling in regulating proliferation and apoptosis (Feng et al., 2019; Rahmani et al., 2020; Samakova et al., 2019; Zhang et al., 2020a; Zhang et al., 2021; Zhang et al., 2020b; Zhang et al., 2020c), in this study, we investigated its role in exosome-mediated regulation of AECII proliferation and apoptosis during hyperoxia-induced BPD using hyperoxia rat models.