IGF1R and pulmonary arterial hypertension: Although we mainly focused on the role of mesenchymal Igf1r signaling in the setting of postnatal lung morphogenesis, interruption of perinatal alveolar development also causes lack of reserve lung capacity that may lead to lifelong susceptibility to lung diseases, such as chronic obstructive pulmonary disease and pulmonary hypertension, indicating the potential clinical importance of IGF1R-controlled alveologenesis (39).