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]. This evidence concerns the gene CYP1B1 and pulmonary arterial hypertension.