CYP1B1 and pulmonary arterial hypertension: However, attenuated hypoxic PAH was observed in Cyp1b1−/− mice, whereas the mice administered with potent CYP1B1 inhibitor 2,3′,4,5′-tetramethoxystilbene (TMS) showed significantly attenuated hypoxic PAH, hypoxic + SU5416 PAH.