HMOX1 and pulmonary arterial hypertension: Differential expressions of CYP1A1, CYP1B1, ALDH3A1, GSTA, HMOX1, NQO1, GJA1, TJP2, and DDB2 were used to evaluate transcriptional biomarker responses based on previous research which found these markers to be predictive of PAH carcinogenicity [30,43].