SMURF2 and pulmonary fibrosis: We initially examined repression of the E3 ubiquitin ligases SIAH1, SMURF1, and SMURF2, which have been identified as targets of miR-424 in several cancers as well as pulmonary fibrosis (Imig et al., 2011; Wu et al., 2013; Xiao et al., 2015).