In summary, our findings suggest that endothelial FGFR1 signaling plays a key role in preserving the integrity of the pulmonary vascular barrier, and reveal that activated ROCK2 contributing to EC contraction and gap formation of neighboring ECs is responsible for the exacerbation of ALI/ARDS in Fgfr1iΔEC/iΔEC mice. Here, ROCK2 is linked to acute respiratory distress syndrome.