Determination of dose-dependent enzymatic activity by measuring the conversion of corticosterone to 11-dehydrocorticosterone by cells with variable amounts of enzyme. 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) is induced by graded doses of doxycycline (doxy) indicated by the x-axis in A, CV1-rMR MMTV-Gluc.tet-inducible-r11βHSD2, and B, CHO-rMR MMTV-Gluc.tet-inducible-r11βHSD2 cells. C, CHO-rMR-pBM14-pTAT3-Gluc.tet-inducible-r11βHSD2 cells stably infected 1 to 3 times with the virus 11βHSD2. Results are presented as the mean of percentage of conversion ± SEM. *P less than .05 vs control (0), without doxycycline induction for A and B and without infection of the complementary DNA for r11βHSD2. Mean values based on data from quadruplicate wells were plotted.