Ourstudy challenges these data on the role of APLN in IPAH, indicating that not onlyAPLN but also the Apelin cleaving enzyme Lysosomal Pro-X carboxypeptidase (PRCP),27 a protein also described to promote angiogenesis and vascular repair,28 show elevated expression by PAH ECs. This evidence concerns the gene APLN and pulmonary arterial hypertension.