The IL-11 and IL-11Rα proteins were increased in isolated muscular pulmonary arteries (70–500 μm diameter) from IPF and IPF + PH (Fig. 1A; P < 0.01 vs control subjects), and significantly overexpressed in pulmonary arteries from IPF + PH patients (Fig. 1A and B; P = 0.01 vs IPF patients). Here, IL11RA is linked to idiopathic pulmonary fibrosis.