ACTA1 and pulmonary fibrosis: TGF-β1 can directly stimulate lung fibroblasts to secrete collagens or induce transformation of fibroblasts to myofibroblasts that express α-smooth muscle actin (α-SMA); both are key events in the pathogenesis of pulmonary fibrosis (Horowitz et al., 2007; Tseng et al., 2013; Kasabova et al., 2014; Deng et al., 2015).