PAH patient-derived MVECs effectively lost VE-cadherin expression from cell–cell junctions (1.00 ± 0.07 vs. 0.64 ± 0.22, p < 0.001) and displayed an elongated morphology with F-actin stress fibers gaining collective directionality and spanning the entire cell body. This evidence concerns the gene CDH5 and pulmonary arterial hypertension.