AdGRE.CAT-mediated in vitro time course of CAT activity in HeLa cells upregulated by dexamethasone (Dex). (A) HeLa cells infected with AdRSV.CAT (25 moi), a control vector driven by the RSV-LTR constitutive promoter. (B) HeLa cells infected with AdGRE.CAT (25 moi). For both panels, after 24 hours, cells were incubated with or without dexamethasone (25 nmol/L) for an additional 1 to 48 hours, and CAT activity was quantified relative to total protein concentration. Shown are data for AdRSV.CAT with dexamethasone (▴) or without dexamethasone (▵); and for AdGRE.CAT infection with dexamethasone (•) or without dexamethasone (○). The data are presented as mean ± SEM of three independent experiments.