NFKB1 and infection: NF-κB transcriptional activity was significantly increased 2.5- and 3-fold in Caco-2 cells infected with S. typhimurium at 6 h post-infection in a concentration of 1 × 106 CFU/ml (p≦ 0.05) and 1 × 107 CFU/ml (p≦ 0.01), respectively (Fig. 1a).