The Editorial Office has been made aware of potential issues surrounding the scientific validity of this paper “MiR-203a-3p regulates TGF-β1-induced epithelial–mesenchymal transition (EMT) in asthma by regulating Smad3 pathway through SIX1” DOI: 10.1042/BSR20192645, hence has issued an expression of concern to notify readers whilst the Editorial Office investigates. Here, SMAD3 is linked to asthma.