Fig 4. Inhibition of 4-HBA-mediated cell survival by suppressing HO-1.

(A-B) C6 cells were transfected with HO-1 siRNA or control siRNA and 15 hrs later, were treated with 100 μM 4-HBA for 9 hrs. HO-1 levels were examined at 24 hrs after siRNA transfection (after 9 hrs of 4-HBA treatment) by immunoblotting. Representative photographs are presented (A) and the results obtained from three independent experiments are presented as means±SEMs (B). **p<0.01 versus siRNA-non-transfected/4-HBA treated cells. (C-D) C6 cells were transfected with HO-1 siRNA or control siRNA and 15 hrs after transfection treated with 100 μM 4-HBA for 9 hrs. Cells were then treated with serum-free media (C) or H₂O₂ (100 μM) (D) for 1 hr. Cell viabilities were determined by MTT assay 24 hrs after treating cells with serum-free media (C) or H₂O₂ (D) (48 hrs after HO-1 or control siRNA transfection). Changes in cell survivals observed in three independent experiments are presented as means±SEMs. **p<0.01 between indicated groups.