MAP2K2 and Salmonella Infections: As shown in Fig 6C, the expression levels of the two phosphorylated proteins p-ERK1/2 and p-MEK2 significantly decreased in HeLa cells infected with the IpaJ-expressed WT or ΔpSPI12-PipaJ strain compared with those in HeLa cells infected with the ΔpSPI12 or ΔpSPI12-PipaJC45A strain, indicating that the representative proteins were dephosphorylated during Salmonella infection depending on the C39 protease activity of IpaJ.