CYP1A1 and pulmonary arterial hypertension: In addition, miR-24-3p has also been reported to negatively regulate ARNT (aryl hydrocarbon receptor nuclear translocator), the protein product of which forms a heterodimer with the aryl hydrocarbon receptor that mediates PAH responses, and to down-regulate the metabolism gene CYP1A1 (cytochrome P450 1A1) (Oda et al. 2012).