Fig. 4.

Hyperoxia-induced increase in oxidative stress and activation of the TGF-β pathway and their blockage by curcumin pretreatment. In cultured e19 AIFs exposed to 95% O₂ for 24 h (to determine oxidative stress) and 30 min (to determine TGF-β activation), NADP-to-NADPH ratio and phosphorylated-to-total Smad3 ratio (P-Smad3/T-Smad3) were significantly increased. Similarly, 95% O₂ exposure of e19 AIFs for 24 h caused a significant increase in activin-like receptor kinase (ALK)-5 expression. All these effects were completely blocked by 5 μM curcumin pretreatment. Values are means ± SE; n = 3.