Upon infection of HeLa cells (Fig. 5B), strains carrying the phoN::tviA insertion elicited significantly less luciferase activity than the respective phoN mutants (P<0.01), indicating that TviA is able to reduce the NF-κB activation elicited by the S. Typhimurium orthologues of SopE and SipA. Here, NFKB1 is linked to infection.