A recent scRNA-seq study has shown that patients with systemic sclerosis–associated PAH (SSc-PAH) have altered endothelial cell subphenotypes, altered SMAD signaling, an endothelial-mesenchymal transition (EndMT) phenotype, and that altered VEGF, TGF-β, and members of the TNF superfamily (TWEAK) can regulate this phenotype (19). This evidence concerns the gene TGFB1 and pulmonary arterial hypertension.