SMAD3 and pulmonary arterial hypertension: Proteins known to play a significant role in PAH such as epidermal growth factor, SMAD3 (Z score = 4.48), endothelin 1 (EDN1- Z score = 4.34), hepatocyte growth factor (Z score = 4.19), and vascular endothelial growth factor A (VEGFA; Z score = 4.11) (Table 5) were activated [38–42].