TLR4 and infection: The alveolar wall thickness, W/D values, EMP counts, PAK4 protein, β-catenin protein, CXCL1 protein, BALF neutrophil counts, and selectin levels of the two strains of mice undergoing the same treatment were not different, likely because the short time period (four hours) of mechanical ventilation (not infection) had little effect on the TLR4 pathway.