STEAP4 and pulmonary arterial hypertension: Furthermore, in the SuHx rat model of severe PAH, a profound downregulation of Stamp2 protein was found as compared to healthy controls (p < 0.0001) (Fig. 1c), which was also corroborated by downregulation of Stamp2 transcript levels by qPCR (p < 0.05) (Fig. 1d).