miR-21 is another player observed in pulmonary fibrosis, as its expression contributes to collagen deposition through potentiation of TGF-β signaling (Kwon et al. 2016), whereas miR-29 represses type I collagen, reducing radiation-induced fibrosis through the negative modulation of the TGF-β/Smad signaling pathway (Yano et al. 2018). The gene discussed is TGFB1; the disease is pulmonary fibrosis.