Figure 4.

HO-1 expression is responsible for undifferentiated cell resistance to oxidative stress. Bilirubin supplementation restores viability in differentiated cells exposed to H₂O₂. (a) WB analysis of HO-1 in undifferentiated cells exposed for 24 h to 500 μM H₂O₂ and silenced for HO-1. GAPDH expression have been used as loading control. The bands show one representative experiment of three. (b) % of viability in undifferentiated cells exposed for 24 h to 500 μM H₂O₂ and silenced for HO-1. Some samples have been treated with a scramble siRNA (siNoT) to exclude aspecific cell responses. Statistical analysis: n = 3, *p < 0.05 vs H₂O₂. (c) 4d-ATRA differentiated cells, have been co-treated with 500 μM H₂O₂ and bilirubin (0.5 µM or 1 µM) in order to prevent cell death induced by cell exposure to H₂O₂ alone. The % of viable cells is shown. Statistical analysis: n = 3, ^§p < 0.01 vs ctr; ^#p < 0.05 vs H₂O₂. Full-length blots are presented in supplementary information.