Fig 2.

All E7 CR3 mutants retain the ability to degrade pRb. (A) Dose-dependent degradation of pRb by wild-type E7 in Saos2 osteosarcoma cells. Saos2 cells were transfected with 1 μg of pRb expression plasmid, 0.1 μg GFP expression plasmid, and the indicated amount of wild-type E7 expression plasmid; 48 h posttransfection cells were collected and samples analyzed by Western blotting for pRb, GFP, and actin levels. (B) pRb degradation by E7 mutants. Full-length wild-type E7 or the indicated mutants were transfected with pRb and GFP expression plasmids at a 1:10 ratio of E7 to pRb, and at 48 h posttransfection levels of pRb were analyzed. The blot is a representative image; the bar graphs represent quantified pRb levels normalized to GFP and actin levels. The relative pRb levels are representative of five independent experiments.