TGFB1 and pulmonary arterial hypertension: Increased levels of TGF-β2 and TGF-β 3 were observed in both SSc and SSc-PAH patients, but SSc-PAH had a higher level of TGF-β2 and TGF-β3 compared to SSc [119] Levy et al. found that miR-26 and miR-let-7d levels were significantly decreased in SSc-PAH versus SSc without PAH and bioinformatic analysis showed that both miRNAs-regulated genes belong to TGF-β signaling pathway or Smad binding gene sets [120].