The result showed that the gene set score of the Phd2EC–/– mice was significantly higher than that of WT mice (Figure 4H), which suggesting that the activation of the HIF2α and TGF-β signaling pathways in the Phd2 deficiency mouse endothelial cells presumably resulting in severe pulmonary hypertension. Here, TGFB1 is linked to pulmonary arterial hypertension.