Regarding the RV, changes in the development of MF and the activity of circulating biomarkers under pressure overload conditions, such as matrix metalloproteinases (MMPs), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), galectin-3 (Gal-3), transforming growth factor-β1 (TGF-β1), and endothelin-1 (ET-1), have been repeatedly studied and emphasized in various types of pulmonary hypertension [30,68,69]. The gene discussed is EDN1; the disease is pulmonary arterial hypertension.