To further explore the reason why ITGB4 deficiency induced BPD, transcriptome sequencing was performed on four different developmental stages: pseudoglandular stage (E13.5), saccular stage (P2), alveolar stage I (P7), alveolar stage II (P28).14, 32, 33. The gene discussed is ITGB4; the disease is bronchopulmonary dysplasia.