PDGFRA and Bloom syndrome: To exclude the possibility that BLM directly induces fibroblast-to-myofibroblast differentiation, we performed a primary culture of FACS-sorted PDGFRα+EPCAM−CD45−CD31−LYVE1−CD146− lung fibroblasts and confirmed that BLM administration to fibroblasts did not increase Acta2 expression (Supplementary Fig. 1c).