The article by Marlene Rabinovitch provides an in-depth review of the molecular pathogenesis of pulmonary arterial hypertension (PAH). It highlights recent clinical and experimental studies that have advanced our understanding of the cellular and molecular mechanisms underlying PAH. The genetic abnormalities, particularly those involving the BMPR2 signaling pathway, have been identified as key factors contributing to the disease. The BMPR2 receptor plays a crucial role in regulating vascular cell proliferation, migration, and survival, and its dysfunction leads to an exaggerated proliferative response in vascular cells, resulting in the occlusion of the pulmonary arterial lumen and the obliteration of distal intraacinar vessels. The article also discusses the interplay between genetic predisposition, inflammation, and immune mechanisms in the progression of PAH. It emphasizes the importance of serotonin-like compounds, oxidative stress, and mitochondrial metabolism in the pathobiology of the disease. Additionally, it explores the role of stem and progenitor cells in the regeneration of normal microvessels and the potential of emerging therapies targeting these pathways. Overall, the review underscores the interconnected nature of the molecules and pathways involved in PAH, suggesting that a comprehensive understanding of these mechanisms is essential for developing effective treatments.The article by Marlene Rabinovitch provides an in-depth review of the molecular pathogenesis of pulmonary arterial hypertension (PAH). It highlights recent clinical and experimental studies that have advanced our understanding of the cellular and molecular mechanisms underlying PAH. The genetic abnormalities, particularly those involving the BMPR2 signaling pathway, have been identified as key factors contributing to the disease. The BMPR2 receptor plays a crucial role in regulating vascular cell proliferation, migration, and survival, and its dysfunction leads to an exaggerated proliferative response in vascular cells, resulting in the occlusion of the pulmonary arterial lumen and the obliteration of distal intraacinar vessels. The article also discusses the interplay between genetic predisposition, inflammation, and immune mechanisms in the progression of PAH. It emphasizes the importance of serotonin-like compounds, oxidative stress, and mitochondrial metabolism in the pathobiology of the disease. Additionally, it explores the role of stem and progenitor cells in the regeneration of normal microvessels and the potential of emerging therapies targeting these pathways. Overall, the review underscores the interconnected nature of the molecules and pathways involved in PAH, suggesting that a comprehensive understanding of these mechanisms is essential for developing effective treatments.