FIG. 2.

Dose response for the Prog (A) and the Tet-ON (B) systems. HeLa cells were coinfected with 10 PFU of the respective activator and reporter viruses. Increasing amounts of inducer were added at the start of infection, and cells were harvested at 16 h postinfection. CAT activity was measured and quantitated by PhosphorImager scanning. Error bars indicate standard deviations calculated from three independent experiments.