The expression of miR-424 is decreased in HPV-positive cells. (A) RT-PCR analysis of miR-424 in undifferentiated HFKs and HPV16- and HPV31-positive cells. (B) RT-PCR analysis of miR-424 in undifferentiated and differentiated HFKs or HPV31-positive cells. Differentiation was induced by addition of high calcium media for 96 h. (C) Western blot analysis of loricrin, involucrin, and GAPDH proteins in HFKs and HPV31-positive cells upon differentiation. (D) RT-PCR analysis of miR-424 in HFKs versus HPV31-positive or CIN612 cells. (E) RT-PCR analysis of miR-424 in HFKs expressing LXSN, 31E6, 31E7, and 31E6/E7. (F) RT-PCR analysis of E7 in HFKs expressing HPV31 E6/E7, and HPV31 genomes. The results were normalized to GAPDH. All results are representative of observations from three independent experiments. *, P < 0.05.