PECAM1 and Sepsis: Strikingly, a higher proportion of CD31+ endothelial cells showed pyroptotic death [stained with propidium iodide (PI) and fluorescent-labeled inhibitors of caspase-1 (FLICA)–caspase-1, a key player in pyroptosis (35)] at 48 h after sepsis onset (SI Appendix, Fig. S8B).