In this study, we demonstrated that the three AP-1 recognition sequences of the miR-21 promoter have promoter activity in cervical cancer cells, and we found that this activity decreased when the AP-1 sequences are deleted in a progressive manner, demonstrating a synergistic effect since the presence of AP-1 sequences increased miR-21 promoter activity (Fig. 7). This evidence concerns the gene JUN and cervical carcinoma.