Effect of internal deletion mutants of the E1A protein on the activity of the K18 promoter. (A) Schematic representation of the structure of the mutants. Symbols are the same as in figure 3. (B) SW613-3 (T) and SW613-B3 (NT) cells were transfected with plasmid pK18(80)luc alone (none) or in the presence of the indicated E1A constructs. Results are presented as in figure 3. Error bars represent standard deviation of the mean of at least two experiments.