Figure 1.

Lung phosphorylated extracellular signal-regulated kinases (ERK)1/2 protein levels in neonatal wild-type (WT) mice exposed to hyperoxia. Lung proteins obtained from neonatal WT mice exposed to 21% O₂ (normoxia) or 70% O₂ (hyperoxia) for up to two weeks (n = 6/exposure) were subjected to immunoblotting using antibodies against total ERK1/2, phosphorylated ERK1/2, or β-actin. Representative immunoblot showing total ERK1/2 and phosphorylated ERK1/2 protein expression (A). Densitometric analyses wherein the phosphorylated ERK1/2 band intensities were quantified and normalized to those of total ERK1/2 (B). The values are presented as mean ± SD. Significant differences between the normoxia and hyperoxia groups are indicated by * p < 0.05. Significant differences between the hyperoxia groups are indicated by † p < 0.001 (Two-way ANOVA).