IGFBP5 and Duchenne muscular dystrophy: The putative negative impact of DMD fibroblasts on SC activity has been also related to the increased expression and secretion of the IGF-1 binding protein 5 (IGFBP-5), which might interfere with the pro-myogenic activity of IGF-1, since the neutralization of IGFBP-5 was able to revert the inhibitory effect of the DMD-fibroblast conditioned medium (Figure 1b, lower panel) [48].