Fig. 1.

Critical determinants of pulmonary endothelial barrier function, both previously established and newly identified, as outlined in this perspective. ZO-1, zona occludens protein 1; FAK, focal adhesion kinase; PKC, protein kinase C; ERM, ezrin radixin and moesin proteins; IQGAP-1, IQRas GTPase-activating protein 1; ADAM, a disintegrin and metalloproteinase; AMPK, adenosine monophosphate-activated protein kinase; PAF, platelet-activating factor; TNF-α, tumor necrosis factor-α; VEGF, vascular endothelial growth factor; ROS, reactive oxygen species; Nrf2, nuclear factor (erythroid-derived)-like 2; TRPV4, transient receptor potential vanilloid 4; S1P, sphingosine 1 phosphate; S1PR1, S1P receptor 1; S1PR2, S1P receptor 2; PGE2, prostaglandin E2.