MAPK3 and infection: To examine MAPK responses, BMMs were infected with WT or ∆tolC Schu S4, or left uninfected, and phosphorylated, and total levels of p38, SAPK/JNK, and ERK1/2 were determined at 30 and 60 min p.i. Infection with the Schu S4 ∆tolC mutant triggered increased levels of phospho-p38 at both time points when compared to macrophages infected WT Schu S4 or uninfected controls (Fig. 4; Fig. S2).