Figure 7. E7 interacts with p14^ARF and UBF1.

(A), The GST-E7 fusion protein efficiently pulled down p14^ARF and UBF1. GST-E7 or GST alone was mixed with CaSki cell lysates. UBF1 and p14^ARF were detected by Western blot. (B), E7 interacts with UBF1 only when p14^ARF is expressed. GST-E7 or GST alone was added to H358 Cl19 cell lysates after culture with or without 1 mg/ml doxycyclin (Dox) for 24 hours to induce p14^ARF expression. UBF1 was detected by western blot. (C), Indirect interaction between E7 and p14^ARF. Purified p14^ARF was incubated with GST-E7 or GST alone, immobilized on glutathione resin, and complexes were analyzed for the presence of p14^ARF by western blot. (D), E7 interacts with p14^ARF in H358 cells (p53−/−). Cells were transiently transfected with p14^ARF and E7 expression vectors. Lysates were immunoprecipitated with purified mouse IgG1 (control) or anti-HPV16-E7 antibodies, and immune complexes were detected with antibodies to p14^ARF and to HPV16-E7. (E), E7 interacts physiologically with p14^ARF and UBF1 in CaSki cells. Lysates were immunoprecipitated with purified mouse IgG1 (control) or anti-HPV16-E7 antibodies. Immune complexes were detected with antibodies against p14^ARF, UBF1 and HPV16-E7.