Our previous studies of mdx/Utro(−/−) mice (a severe murine model for DMD; dystrophin−/−; utrophin−/−) revealed the greatly increased number of SA-β-gal (Senescence-associated β-Galactosidase) + senescent cells in the dystrophic muscles, which is closely associated with severe dystrophic phenotypes [3, 4]. The gene discussed is DMD; the disease is Duchenne muscular dystrophy.