Knockdown of endogenous HPV18 E6 in HeLa cells with HPV18 E6-specific siRNA (siE6) significantly suppressed mRNA expression of AREG. Each bar represents mean ± SEM (n = 4). Bars with different letters are significantly different from each other (siCtrl vs. siHPV18E6, P = 0.0181; siCtrl vs. siYAP, P = 0.0005). 