Writing in Circulation at nearly the same time, Ranchoux et al. reported that analysis of endothelial cell-cell junction, and endothelial and subendothelial cell phenotype in intimal and plexiform lesions from PAH lungs relative to control non-tumor lung specimens, was carried out using unambiguous endothelial (CD31, CD34, VE-cadherin) and mesenchymal α-SMA markers. Here, ACTA1 is linked to pulmonary arterial hypertension.