Figure 2.
Effect of E7 mutants on C/EBPα-induced proliferation arrest. Schematic representation of E7 wt and mutant constructs used. CRs are indicated at the top. Within CR2 the pocket protein-binding motif and the CKII phosphorylation motif are indicated by hatched areas. The amino acid sequence of the wt HPV-16 E7 CR2 is shown below that. The pocket protein-binding and CKII phosphorylation motifs are indicated by bold letters, and point mutations are shown below them. (A) BCER cells were stably transfected in triplicates with pBabePuro constructs as indicated in the individual plots. Growth curves were determined (means of triplicates and SDs) from pools (approximately 200 colonies per pool) of transfected cells grown in the presence (●) or absence (○) of estrogen (0.5 μM). (B) Immunoblot analysis of HA epitope-tagged E7 constructs. BCER cells were infected with recombinant retroviruses encoding 16E7 (lane 1), 16E7ΔCR2 (lane 2), 16E7gly24 (lane 3), E7ala13/32 (lane 4), 1E7 (lane 5), and 6E7 (lane 6). Nuclear extracts were examined by Western blotting.