ACE and bronchopulmonary dysplasia: Its known involvement in branching morphogenesis and alveolization could account for a role in the developmental arrest of BPD.[28,34] Other dysregulated factors of pulmonary development include SPP1 (downregulated during secondary septation [27]), CAV1(involved in alveolar septation [35] and acute lung injury [36]) and ACE (involved in secondary septation [37]).