THBS1 and oral submucous fibrosis: Several genes involved in EMT induced by TGF-β were identified including secreted frizzled-related protein-4 (SFRP4), thrombospondin 1 (THBS1), MMP-2, and Charcot Leyden Crystal-18 (CLC-18), suggesting its important role in the pathogenesis and malignant transformation of OSMF [19].