RB1 and cervical cancer: While most of the RNAi studies against HPV are carried out in cervical cancer cells or animal models, several studies have demonstrated that in the HR-HPV HNSCC cell line, E6- and/or E7-targeting shRNA or siRNAs can downregulate E6 and E7 and upregulate the expression of p53 and pRb proteins [81,82,83].