In contrast, under hyperoxic conditions, the expression of the 6 retinoid receptors were significantly reduced at P4 (RARγ, RXRα), P9 (RARα, RARβ, RXRγ), and P15 (RARβ, RARγ, RXRα, RXRβ, RXRγ), which could interfere with alveologenesis and contribute to BPD development. The gene discussed is RARB; the disease is bronchopulmonary dysplasia.