HDAC6 and cervical cancer: To further investigate the regulatory effect of the E7 gene on HDAC6 and DNMT3B in HPV-negative cervical cancer cells, we infected C33A cells with recombinant viruses expressing the E7 gene (Ad4-HPV16E7, Ad4-HPV16E6E7, Ad4-HPV18E7, and Ad4-HPV18E6E7).