Figure 4: Western analysis of signaling proteins upstream of PAI-1. (a–c) Western analysis (upper) of (a) TGF-β, (b) total and phosphorylated Smad3, and (c) total and phosphorylated PKA and quantitation (lower) in lungs at 16 weeks after irradiation. Band densities were normalized to those of β-actin. Values are expressed relative to control and are the mean ± SEM . versus control group; versus IR group. PAI-1, plasminogen activator inhibitor-1; TGF-β, transforming growth factor-β; PKA, protein kinase A; PTX, pentoxifylline.