RAF1 and pulmonary arterial hypertension: It is noteworthy that in the model of genetic forms of pulmonary hypertension-BMPR2 loss-of function-ERK1/2 are constitutively activated and two Raf inhibitors (Sorafenib and AZ628) as well as Nintedanib (a triple receptor tyrosine kinase inhibitor acting upstream) reversed the invasive proliferation of the pulmonary artery endothelial cells [43].