In order to examine if HPV infection has any effect on AP-1 binding activity in esophageal cancer, as depicted in representative photograph in Figure 3A, we observed a differential activation of AP-1 in ESCC; an elevated AP-1 DNA-binding activity was significantly higher in HPV-positive tumors as compared to that in HPV-negative tumor tissues. Here, JUN is linked to esophageal squamous cell carcinoma.