Heat map of microarray analysis and the corresponding values of fold change for the 70 significantly upregulated or downregulated genes of in vitro M cells and Caco-2 cells after infection with wild-type (WT) S. Typhimurium and ΔspeG or remaining uninfected for 1 h.

We found 70 genes of in vitro M cells and Caco-2 cells that were significantly upregulated (>2-fold change, red bricks) after treatment with WT S. Typhimurium SL1344, the speG-deleted mutant (ΔspeG), and only Luria-Bertani broth (LB). These 70 genes were classified into 8 groups according to their relative or potential functions. Red bricks represent higher gene expression levels compared with average levels (black bricks).