Fig. 4.

Induction of heme oxygenase-1 (HO-1) by H₂O₂ treatment and by 3% oxygen tension. (A) Human fibroblast IMR-90 cells were treated with 600 μM of H₂O₂ for 2 h and then cultured in H₂O₂-free medium and harvested at the indicated time points for Western blotting. Culture conditions for this experiment were 20% oxygen tension. (B) NRK and INS-1 cells were cultured under 3% and 20% oxygen tensions for 5 weeks and then harvested for Western blotting. Two replicates for each condition were analysed. (C) NRK cells were treated with the indicated concentrations of H₂O₂ for 2 h and then cultured in H₂O₂-free medium for a further 5 h until harvested for Western blotting. INS-1 cells were treated with the indicated concentrations of H₂O₂ for 7 h before harvested for Western blotting. Culture conditions for this experiment were 20% oxygen tension. Equal loading was confirmed using an anti-actin antibody and Coomassie blue staining respectively.