iNOS mediates the S-nitrosylation of Hsp90 at Cys521. A: HUVECs were treated by oxLDL (100 μg/mL) for 24 h. The levels of iNOS, p-eNOS, eNOS, GSNOR and TRX were detected by Western blot. (n = 5, ***P < 0.001). B: HUVECs were pre-incubated with 1400W (an iNOS inhibitor, 10 μM) for 1 h followed by treatment with oxLDL for 24 h. The SNO-Hsp90 levels were detected by biotin switch. (n = 5, ***P < 0.001). C: Primary mouse aortic endothelial cells (MAECs) were isolated from WT and iNOS-/- mice, followed by oxLDL treatment for 24 h. The SNO-Hsp90 levels were detected by biotin switch. (n = 3, **P < 0.01). D: Construction of mutagenesis Hsp90 plasmids by substituting the Cys521 with the non-nitrosylable alanine. E: EA.hy926 endothelial cells were transfected with Hsp90-WT or Hsp90-C521A plasmids for 24 h, followed by exposure to oxLDL for 24 h. The SNO-Hsp90 levels were detected by biotin switch. (n = 6, ***P < 0.001).