FIG. 8.

Effect of 16E5 on ERK and 16E1^E4 phosphorylation. (A) RT-PCR was carried out with a 16E5-expressing SiHa cell line to detect the presence of E5-encoding mRNA. SiHa cells transfected with empty plasmid were used as the negative control. For the positive control, the plasmid pMT3H16E5KC was used as the template for the PCR. (B) E5-positive or E5-negative SiHa cells were infected with rAd16E1^E4 for 24 h and incubated with 10 ng/ml EGF or 0.5 M sorbitol for 10 min prior to harvest. Cell extracts with (+) or without (−) EGF or sorbitol treatment were analyzed by Western blotting with antibodies against active ERK, GAPDH, 16E1^E4, or T57-phosphorylated 16E1^E4 (phospho T57). Molecular mass standards (in kilodaltons) are shown to the left.