TGFB1 and idiopathic interstitial pneumonia: In hypertrophic scar and keloid fibroblasts, miR-21 expression is elevated ~2.5–4.2-fold compared with normal skin (p < 0.01), driving TGF-β/Smad and PI3K/Akt activation by suppressing Smad7 and PTEN [37,38,39,40,41], while in plasma from 88 IPF patients, miR-21 levels were elevated approximately 2-fold compared to healthy controls (p < 0.001) [156].