MC1R and keloid: In addition, MC1R mRNA expression levels in keloid fibroblast cell lines were reduced to less than 50%, in comparison with the normal fibroblasts [157], and α-MSH administration to keloid fibroblasts did not inhibit TGF-β1-mediated collagen synthesis and myofibroblast differentiation as much as in the control group, seemingly because of defective expression of MC1R in keloid fibroblasts [179].