CLIC4 protein expression in patient plasma, human ECFCs and rat lung. (A) CLIC4 protein levels in plasma samples from IPAH patients (n=123) and healthy volunteers (n=64). As these data show a skewed distribution they were analysed using the Mann-Whitney U-test. (B) Levels determined in blood-derived endothelial cells from IPAH patients (n=4–5). (C) CLIC4 protein expression in the lungs of rats treated with monocrotaline (MCT) or (D) exposed to hypoxia (n= 3–8). Data are presented as mean±SEM. *P<0.05; **P<0.01, compared with controls. Lung sections from (E i) control, (E ii) hypoxia-, (E iii–iv) MCT and (E v–vi) Sugen 5416/hypoxia-induced pulmonary hypertensive rats, demonstrating co-localisation of CLIC4 and von Willebrand factor (vWf) in the pulmonary endothelium (arrows) of normal and remodelled pulmonary arteries. Arrowheads (E iii, v) indicate CLIC4 immunoreactivity in smooth muscle cells. Bar=50 μm.