Hypoxia also induces exocytosis of Weibel-Palade bodies (WPb) from ECs, which contain von Willebrand Factor (vWF) (Pinsky et al., 1996) and clinical studies suggest that increased plasma vWF is a biomarker of endothelial dysfunction in cardiovascular disease (Conway et al., 2002; Horvath et al., 2004). Here, VWF is linked to endothelial dysfunction.