Gao, Ling & Wu (1997) reported in 1997 that the mRNA level of TGF-β1 was the highest expressed in OSF epithelial tissue compared to the healthy mucosal tissue and oral lichen planus. In addition, our previous study also confirmed that TGF-β1 was predominantly expressed in OSF epithelium, which was significantly higher than that in healthy mucosal epithelium (Wang et al., 2018). Here, TGFB1 is linked to oral lichen planus.