IGF1 and pulmonary arterial hypertension: Additionally, growth factors such as vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), insulin-like growth factor-1 (IGF-1), and epidermal growth factor (EGF), play an important role in the maladaptive vascular remodeling responsible for the rise in the PVR in PAH (Figure 1) [6,8,18].