PECAM1 and endothelial dysfunction: Pichler Hefti et al. subjected healthy volunteers to hypobaric hypoxia and only found elevated levels of CD62E+/CD144+ EMPs, but not of AnnexinV+/CD31+ EMPs, indicating that endothelial dysfunction caused by hypoxia is induced by endothelial activation (Pichler Hefti et al., 2016).