Nox4 has been found to have roles in metabolic adaptations of skeletal muscle to physical activity,27 to act as an oxygen sensor that modulates muscle contractility in proportion to tissue oxygen levels,18 and to inhibit tissue repair in a mouse model of muscular dystrophy.33 Consistent with the previously reported role of Nox4 in increasing muscle contractility when tissue oxygen levels are high,18 we observed a small decrease in specific force- generating capacity of EDL muscle from MyoD-Cre/Nox4(f/f) although this did not reach our threshold for significance. The gene discussed is NOX4; the disease is muscular dystrophy.