Western blot and immunofluorescence showed that the expression of SP‐C (AECII‐specific surface marker) and Hop‐X (AECI‐specific surface marker) were significantly decreased, while α‐SMA was significantly increased in BPD (Figure 1C,D), suggesting that the differentiation of AECII to AECI was decreased and the transdifferentiation of AECII was impaired in BPD. The gene discussed is HOPX; the disease is bronchopulmonary dysplasia.