TLR4 and atherosclerosis: Finally, we investigated expression of endothelial dysfunction markers in aortic arch from both WT and MerTK-/- mice such as NF-kB, TLR4, vWF (von Willebrand factor, is known to contribute to atherosclerosis) 25, VACAM-1 (vascular cell adhesion molecule 1) and NADPH oxidase subunit p22phox (responsible for ROS production) 26.