In PAH, lineage tracing enabled the identification of both partial and complete EndMT states with distinct marker profiles.73 In this study, the partial EndMT cells expressed endothelial progenitor cell markers such as prominin-1 (PROM1/CD133) and CD34, while fully transitioned cells coexpressed mesenchymal stem cell markers such as the stem cell antigen 1 (SCA1) and endoglin (ENG/CD105).73 Of note, ENG is expressed in vascular ECs but it further increases in mesenchymal-like cells. This evidence concerns the gene ENG and pulmonary arterial hypertension.