CYBB and systemic inflammatory response syndrome: Consistent with greater citrullination of H3 in the lung of gp91phox−/y mice following induction of SIRS, PAD4 activity was greater in the lung of mice lacking Nox2 following SIRS induction, and PAD4 activity in the lung of mice lacking Nox2 was significantly higher at 24 h than at baseline (Figure 8C).