Fig. 5.  Activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) in myeloid differentiation factor 88 (MyD88)-wild-type (WT) mice after high tidal volume (HTV). A representative Western blot of expression of inhibitor of κBα (IκBα) (A ) and MAPK- extracellular signal-regulated kinase (ERK) phosphorylation, phosphorylated ERK (B ) in lungs isolated from MyD88-WT and MyD88 knockout (KO) mice 4 h after spontaneous breathing with tracheotomy (control [CON]) and mechanical ventilation with HTV from three independent experiments. All data are presented as mean ± SD. *P < 0.05 compared with CON mice. RDU = relative densitometry units.