CYP1B1 and pulmonary arterial hypertension: In female mouse lung tissue, except for an increase in estrogen receptor α gene expression (ESR1), MA treatment did not affect gene expression of receptors shown to contribute to PAH such as BMPR2 and HTR1B. No changes were observed in gene associated with estrogen metabolism (CYP1A1 and CYP1B1), as well as genes associated with remodeling and fibrosis (TGFβR1, cola1a1, col3a1 and FN1) (Fig. 5A).