MAPK3 and infection: Consistent with previous work, infection with WT, OspF-complemented, or SpvC-complemented Shigella efficiently prevented p38 and ERK1/2 phosphorylation, whereas ΔospF, KLA-complemented, or avirulent (virulence plasmid-cured) BS103 Shigella triggered robust MAPK phosphorylation (Fig. 2C).