RARA and bronchopulmonary dysplasia: 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.