CTSL and pulmonary arterial hypertension: Cathepsin L inhibition by short hairpin RNA (shRNA) can attenuate PAH in MCT- and Su/Hx-induced rats by restoring BMPR2 expression.64 Isorhamnetin reduces inflammatory factors and improves BMPR2 signaling in MCT-PAH rats.396 Overall, normal BMPR2 expression is vital for pulmonary vascular health, and its deficiency promotes PH progression through inflammation and cellular changes.