PTGIS and pulmonary arterial hypertension: In Stearman’s study [8], differentially regulated drug targets in PAH, including EDN1, EDNRA, PDE5A, GUCY1B1, PTGIR, PTGIS, and CACNA1C, which are related to the endothelin pathway, phosphodiesterase family, prostanoid pathway proteins, and voltage-gated calcium channels, were demonstrated.