Consistent with a potential role for gal-3+ macrophage–derived Spp1 in the pathogenesis of muscular dystrophy, Spp1 enhances the matrix metalloproteinase 9–mediated processing of TGF-β into its active form to promote muscle fibrosis in mdx mice (22, 23, 30). The gene discussed is TGFB1; the disease is muscular dystrophy.