Fig. 3. Induced HEK293-HO-1 cells expressed HO-1 protein and exhibited a decreased rate of respiration. (A) HEK293-HO-1 cells were induced to express HO-1 protein by treatment with 1 µg/ml tetracycline (Tet) for 24 hours. The expression was compared with that of Hep3B cells treated with known inducers of HO-1; LPS (1 µg/ml and 50 µg/ml), CoCl2 (200 µM) and haemin (10 µM). (B) The respiration of induced HEK293-HO-1 cells incubated under ambient O2 concentrations (ii) and hypoxic conditions (iii) was decreased compared with that of non-induced cells (i). Tracings and western blots are representative of at least three independent experiments.