BMPR1B and pulmonary arterial hypertension: Zhong et al. identified BMPR1B as a growth-related gene in Tibetan sheep [13], but our study demonstrated it also regulates pulmonary artery smooth muscle proliferation (via TGF-β signaling) to mitigate high-altitude pulmonary hypertension—a function critical for Tibetan sheep’s survival at 3200–3500 m.