Depletion of Tsc1 or Tsc2 in adult lung epithelium, smooth muscle, or vascular endothelium demonstrated that the activation of mTORC1 drove cell senescence, loss of lung alveolar structure, and the appearance of emphysema with pulmonary hypertension and significant vascular remodeling in male mice (13). Here, TSC1 is linked to pulmonary arterial hypertension.