Because IFN-γ protein and mRNA expression were very high in influenza-infected Tpl2-/- mice (Figures 2C and 4D) and have been reported to induce damage via NOS2 (49), we also examined whether IFN-γ correlated with NOS2 mRNA expression and did not find any correlation (Figure 4X). This evidence concerns the gene NOS2 and influenza.