lpxO deletion in A. baumannii results in upregulation of inflammatory responses in macrophages upon infection. (A) tnfα expression in iBMDMs infected for 5 h with UV-killed A. baumannii ATCC 17978, A. baumannii ΔlpxO mutant (ΔlpxO), and A. baumannii ΔlpxO::Tn7lpxO mutant (ΔlpxO::Tn7lpxO) by reverse transcriptase quantitative real‐time PCR. Values are presented as the means ± SD from three independent cDNA preparations measured in duplicate. (B) TNF-α secretion by iBMDMs stimulated for 5 h with UV-killed A. baumannii ATCC 17978, A. baumannii ΔlpxO mutant (ΔlpxO), and A. baumannii ΔlpxO::Tn7lpxO mutant (ΔlpxO::Tn7lpxO). In panels A and B, P values were <0.05 (*) and <0.0001 (****) versus A. baumannii ATCC 17978, determined using one-way ANOVA with Bonferroni contrasts. (C) Immunoblot analysis of IκBα and tubulin levels in lysates of iBMDMs infected with UV-killed A. baumannii ATCC 17978, A. baumannii ΔlpxO mutant (ΔlpxO), and A. baumannii ΔlpxO::Tn7lpxO mutant (ΔlpxO::Tn7lpxO) for the indicated times. (D) Immunoblot analysis of phospho‐JNK (pJNK), phospho‐ERK (pERK), phosphor-p38 (pp38), and tubulin levels in lysates of iBMDMs infected with UV-killed A. baumannii ATCC 17978, A. baumannii ΔlpxO mutant (ΔlpxO), and A. baumannii ΔlpxO::Tn7lpxO mutant (ΔlpxO::Tn7lpxO). In panels C and D, data are representative of at least three independent experiments.