Figure 5: AGEs could inhibit eNOS phosphorylation through RAGE-MAPK signaling pathways but NF-κB pathway not involved (effects of NF-κB, ERK, and P38 inhibitors on AGE-induced eNOS phosphorylation decrease). (a and b) The proteins eNOS and p-eNOS were detected by Western blotting. (c and d) Densitometry analysis of eNOS and p-eNOS is shown. AGEs suppressed the activation of eNOS through RAGE, and the effect was inhibited by blocking ERK (PD98059) or p38 MAPK pathway (SB202190), but not inhibited by blocking NF-κB pathway (helenalin). AGEs: Advanced glycation end-products, RAGE: Receptor for advanced glycation end-products, HUVECs: Human umbilical venous endothelial cells, NF-κB: Nuclear factor-kappa B, MAPK: Mitogen-activated protein kinase, PCR: Polymerase chain reaction, eNOS: Endothelial nitric oxide synthase