Figure 2

SP-A mRNA levels in the presence or absence of insulin (2.5 μg/ml) and/or signal transduction inhibitors in human fetal lung explants. Explants were grown for 6 days, then treated with inhibitors plus or minus insulin or vehicle for 12 hours (wortmannin experiments) or 24 hours (rapamycin and PD98059 experiments), harvested and analyzed for human SP-A mRNA. Data representative of two experiments with similar results are shown. (A) Wortmannin (100 nM) abolished the insulin-mediated inhibition of SP-A gene expression. (B) Rapamycin (50 nM) inhibited the insulin-mediated decrease in SP-A mRNA level. (C) PD98059 (2.5–10 μM) decreased basal SP-A mRNA levels in a dose-dependent manner, but had no effect on the insulin-mediated inhibition of SP-A gene expression. SP = surfactant protein