HBO increases AP-1-binding activity and visfatin promoter activity. A, Representative EMSA showing protein binding to the AP-1 oligonucleotide in nuclear extracts of human CAECs after HBO treatment in the presence or absence of inhibitors and TNF-α antibody. Similar results were found in another two independent experiments. Cold oligo means unlabeled AP-1 oligonucleotides. B, Constructs of visfatin promoter gene. Positive +1 demonstrates the initiation site for the visfatin transcription. Mutant visfatin promoter indicates mutation of AP-1 binding sites in the visfatin promoter as indicated. C, Quantitative analysis of visfatin promoter activity. The luciferase activity in cell lysates was measured and was normalized with renilla activity (n = 4 per group). *P < 0.001 vs. control.