The inhibitor of PTGS2 celecoxib could decrease the expressions of VCAM-1, ICAM-1, and TNF-α in HUVECs induced by LPS, and significantly inhibit LPS-induced attachment of monocytes to HUVECs, while the agonists rebamipide attenuated the inhibition effect of quercetin on adhesion molecules VCAM-1, ICAM-1, and pro-inflammatory cytokine TNF-α as well as the number of monocytes attached to endothelial cells (Figure 7), suggesting that high-expression PTGS2 might be the target of quercetin and inhibition of PTGS2 may improve endothelial dysfunction by reducing adhesion of endothelial cells. Here, VCAM1 is linked to endothelial dysfunction.