FIG. 4.

Western blot analysis of phospho-ERK1/2 (p44/42) in macrophages infected with Salmonella. Cytosolic extracts prepared at the indicated times after infection with wild-type (WT), spiC, or purB Salmonella strains were analyzed with phospho-ERK1/2 and ERK1/2 antibodies. (A) Image of the original blots. After analysis with an anti-phospho-ERK1/2 antibody (top), the membranes were stripped and reprobed with an antibody directed to ERK1/2 (bottom). (B) Densitometric analysis of the amounts of phospho-ERK1 (pP44) normalized to the amount of ERK1 in the same sample. The graphs show percentages of the value in uninfected macrophages. The data are the means and SD of three independent experiments. ∗, P < 0.01; ∗∗, P < 0.005 (significantly different from macrophages infected with spiC Salmonella). UI, uninfected.