ACTA1 and idiopathic pulmonary fibrosis: Analyses of two independent human IPF/UIP datasets (GSE32537 and GSE10667) revealed that both ACTA2 (encoding α-SMA), a common activated fibroblast marker, and MSI2 mRNA were upregulated in IPF/UIP as compared to normal lung tissues (Fig. 1J), suggesting an increased MSI2 in activated lung fibroblasts.