BM in the pathogenesis of PH and RV disease. CAV-1–deficient BM from CAV^−/− mice with hypoxia induces pulmonary vascular remodeling and RV hypertrophy. WT BM can protect CAV^−/− mice from RV disease that occurs with aging, but not PV disease. Disease-producing BM is skewed to megakaryocyte/erythroid lineage differentiation.