Although the mechanisms leading to the increased levels of MMP-9 remain unknown, proinflammatory cytokines whose abundance is increased in mdx mice, appear to be some of the potential stimuli for up-regulation in MMP-9 levels in skeletal and cardiac muscle in muscular dystrophy (Acharyya et al., 2007; Li et al., 2009a; Shin et al., 2013). The gene discussed is MMP9; the disease is muscular dystrophy.