Additional insight into the critical importance of pericyte-endothelial cell interactions in PAH was provided in a study by Wang et al., showing that the loss of prolyl hydroxylase domain protein 2 (PHD2) in endothelial cells increased pericyte recruitment to vessels and led to PAH in the absence of any additional insult (Wang et al., 2016). Here, EGLN1 is linked to pulmonary arterial hypertension.