While there were no genes upregulated in PAH cluster 8, control PAEC cluster 8 had upregulated expression of genes controlling the enzyme-linked-receptor-protein-signaling pathways inhibin subunit beta A (inhba), follistatin like 3 (fstl3), zinc finger protein 703 (znf703), hedgehog interacting protein (hhip), eph receptor B6 (ephb6), integrin subunit beta 3 (itgb3) and plasminogen activator, tissue type (plat). This evidence concerns the gene HHIP and pulmonary arterial hypertension.