In agreement with results showing that miR-21 is induced in BLM fibrosis [15], this study found that miR-21 levels progressively increased during collagen production at SBRT-damaged sites, accompanied by the significant downregulation of several miR-21 targets, including Smad7, suggesting that increased miR-21 contributes to fibrotic responses. Here, SMAD7 is linked to Bloom syndrome.