ACTA1 and pulmonary arterial hypertension: Exposure to 100% O2 for 10 days induced vascular remodeling with increased pulmonary arterial medial wall thickness (2.5-fold, p < 0.001; Figures 8A,B), determined on αSMA-stained (Figure 7C) and on elastin-stained sections (Figure 7G), and increased muscularization of small arterioles (1.5-fold, p < 0.001; Figure 8C), determined on αSMA (brown) and vWF (blue) double stained sections (Figure 7K), as markers for vascular remodeling and PAH.