NOX4 and cardiac hypertrophy: At baseline, i.e., in the absence of pressure overload, Zhang et al. observed that their Nox4-transgenic mice—with significant elevation of myocardial H2O2 production—had a slight cardiac hypertrophy in 12-month old mice compared with WT littermates, although Nox4-transgenic mice were grossly normal and showed no cardiac dysfunction at 3 months (Zhang et al., 2010), suggesting a deleterious chronic cardiac effect of NOX4.