MMP1 and systemic sclerosis: miR-let-7g was found upregulated in SSc skin tissue [87] and upregulated miR-92a expression was detected in cultured dermal fibroblasts from SSc skin, leading to the down-regulation of Matrix Metalloproteinase (MMP)-1, which results, in turn, in the excessive accumulation of collagen by decreasing collagen degradation [88,89].