FIG. 3.

Transactivation of the cyclin A promoter is a J-domain-dependent, Rb-binding-independent T-antigen activity. TC7 cells were transfected with the reporter pAluc and the DNA indicated. (A) Transient transfection assays performed with medium containing high or low concentrations of serum (hs or ls, respectively). (B) Results obtained with hs. Since transactivation levels are influenced by the plasmid backbone of constructs expressing T antigen (7), the mutants in each experiment were examined in relation to wild-type T antigen expressed from the same plasmid backbone.