Fig. 3.

The Rb binding domain of E7 is necessary for increased levels of E2F1 and E2F2 in HPV positive and E7-expressing keratinocytes. (A) Whole cell lysates were harvested from HFKs, HFKs containing wild-type HPV31 genomes (HFK-31), or HPV31 genomes containing an E7 Rb deletion mutant (HFK-31 ΔLHCYE) that were undifferentiated (T0) or differentiated for 24 or 48 h in methylcellulose (MC). Western blot analysis was performed using antibodies to E2F1, E2F2, and E2F3. GAPDH served as a loading control. The Western blots shown are representative of five independent experiments across four HFK backgrounds. (B) Whole cell lysates were harvested from HFKs stably transduced with a retroviral control vector (pLXSN), or vector expressing wild-type HPV31 E7 (pLXSN-31 E7), or an E7 containing a mutation in the Rb (pLXSN-31 E7-ΔLHCYE) that were undifferentiated (T0) or differentiated in methylcellulose for 24 and 48 h. Western blot analysis was performed as described in Panel A. Shown are Western blots representative of three independent experiments across two HFK backgrounds.