Proposed model for GAG-hed modulation of AP1 transcription factor in HPV18 LCR. Fos-Jun/AP1 transcription factor complex is bound off in the presence of GAG-hed. GAG-hed-AP1 complex is rendered stable and unable of binding to DNA. Model in based in data reported in previous work [30,69] and particularly adapted to HPV18-LCR. Circular HPV18 genome showing the early and late open reading frames (ORF). The LCR has been expanded to show clearly the promoter and enhancer regions in front of E6 and E7 genes. The AP1 binding sites located in the promoter and the enhancer are indicated. Apart from the TATA sequence, the other known binding sites for transcription factors in the LCR of HPV18 have not been indicated.