PDGFRB and pulmonary arterial hypertension: As key mechanisms, imatinib reversed overexpression and increased phosphorylation of PDGFRβ in pulmonary arteries from rat models of pulmonary hypertension, inhibited PDGFR-related ERK1/2 activation in lungs of these animals thereby suppressing rat pulmonary artery smooth muscle cell (PA-SMC) proliferation and inducing PA-SMC apoptosis [13].