PI3K/AKT activation was involved in ghrelin-mediated lung endothelial cell barrier protection in vitro. The PI3K inhibitor, LY294002 (20 μM), was added 30 min before ghrelin (100 nM) treatment. LPS was added 30 min after ghrelin treatment. A and B, Western blot analysis showed that ghrelin participated in the activation of the PI3K/AKT pathway, which was diminished under LPS insulting, and LY294002 reversed this effect. C and D, Western blot analysis showed that LY294002 inhibited the antiapoptotic protein Bcl-2 and proapoptotic protein Bax. E, the scratch-wound test indicated that the motility of endothelial cells was inhibited by adding LY294002. F, tube formation assay suggest that ghrelin promotes the vascular tube formation under LPS exposure but is reversed by the PI3K inhibitor LY294002. G and H, quantitative analysis of the wound confluence rates and numbers of tube formation are shown in the bar graphs. The data are presented as the mean ± SEM, n = 6, ∗p < 0.05 compared with the control group, #p < 0.05 compared with the LPS group, ∗∗p < 0.05 compared with the ghrelin + LPS group. LPS, lipopolysaccharide.