TGFB1 and pulmonary arterial hypertension: In this study, we demonstrated that circ-Ntrk2 expression is upregulated in hypoxic lung tissues and PASMCs and that its deficiency could improve pulmonary vascular remodelling and relieve PAH via the miR-296-5p/TGF-β1/p38 MAPK signal transduction axis, thus establishing potential targets for PAH diagnosis and treatment.