ACTA1 and fibrosis: Steensel et al. (2009) showed that the expression of TGF-β1 mRNA in the orbital tissue of GO patients was twice that of normal people. In addition, by detecting the expression level of TGF-β1 in muscle, it was found that the expression level of TGF -β1 in mice with fibrosis was much higher than that in the control group. Thus, it was speculated that TGF-β1 could induce the differentiation of α-SMA protein into MFBs by inducing fibroblasts to express α-SMA, and then induces the occurrence of muscle fibrosis (Liu et al., 2016).