NOX4 and ischemic stroke: To further examine whether the neuroprotective effect observed in Nox4−/− mice is specifically related to reduced ROS formation and not due to other nonspecific or developmental defects, we performed a rescue experiment by restoring cerebral ROS levels in Nox4−/− mice during the course of ischemic stroke by applying exogenous H2O2 (Figure 4B–4D).