In contrast to its promoting effect on the myogenic differentiation of DMD myoblasts, sPIF inhibited the fibrogenic differentiation of these cells and decreased the expression of collagen 1A1 and 1A2 and that of TGF-β (Fig. 1e), which plays a major role in fibrogenesis. This evidence concerns the gene TGFB1 and Duchenne muscular dystrophy.