None of the CBNP increased the mRNA expression of Gpx3 or Gr. In intrapulmonary airways PAH-containing CBNP induced a similar expression pattern of Cyp1a1 mRNA compared to the tracheal epithelium; no increase of mRNAs for anti-oxidative enzymes was detected (Additional file 11). Here, CYP1A1 is linked to pulmonary arterial hypertension.