Moreover, MMP-1 and MMP-3 may be principally associated with ero­sion development.[18] Tsai et al. were the first who elu­cidated the circulating plasma expression of MMPs in OLP.[19] They reported that MMP-2 overexpression in OLP is consistent with its upregulation in peripheral serum. This evidence concerns the gene MMP1 and oral lichen planus.