Objective To determine the dynamic expression of E2F1 gene in lung fibrolasts of neonatal rats with chronic lung disease(CLD),and to elucidate the biological effects of E2F1 in pulmonary interstitial fibrosis of CLD.Methods Full-term newborn SD rats were continuously exposed to 85% oxygen(hyperoxia group) or room air(room air group) within 12 hours after birth.The rat pups were randomly selected to be killed on postnatal day 3,7,14 and 21,lungs were immediately resected under sterile condition and primary c...