In vivo upregulation of CAT activity in the liver by dexamethasone (Dex) after intravenous administration of the AdGRE.CAT vector to C57B1/6 mice. (A) Dexamethasone-induced expression of CAT as a function of vector dose. The AdGRE.CAT vector (10⁸, 5 × 10⁸ or 10⁹ pfu) was administered intravenously to C57B1/6 mice and 24 hours later, dexamethasone (50 μg) was administered intraperitoneally. (B) Expression of CAT as a function of dexamethasone dose. The AdGRE.CAT vector (5 × 10⁸ pfu) was administered intravenously to C57B1/6 mice, and 24 hours later various doses of dexamethasone (1, 5, 10, 50, 100, 500 μg) were administered intraperitoneally. Two days later, CAT activity was quantified in the liver. Shown are data for AdGRE.CAT infection with dexamethasone (•) or without dexamethasone (○). The data are presented as mean ± SEM of three experiments.