BMPR2 and pulmonary arterial hypertension: Bmpr2+/- mice express about 50% of Bmpr2+ mRNA levels and manifest little [18] or no [23,24] pulmonary hypertension at baseline; however, pulmonary hypertension induced by an inflammatory stress [24] or an infusion of serotonin [23] is more marked in Bmpr2+/- than in WT mice.