Indeed, S. aureus challenge induced increased expression of Defβ14 (Figures 5C, D), RegIIIg (Figures 5G, H), and LCN2 (Figures 5I, J) in both the lungs and trachea, which have been shown to play important roles in S. aureus-induced pneumonia (34–37). This evidence concerns the gene LCN2 and susceptibility to pneumonia measurement.