LYN and susceptibility to pneumonia measurement: To investigate the physiological relevance of Lyn in P. aeruginosa infection, we intranasally instilled laboratory strain PAO1 at 1×107 CFU for each Lyn−/− mouse (Supplementary Figure 1A) as well as WT control mouse (with otherwise similar genetic backgrounds) to establish an acute pneumonia model and compared the survival rates of these two groups of mice (10 mice per group).