CAT and infection: The activities of GSH-Px, SOD, CAT, GCL, and T-AOC were significantly reduced at 3 h and 5 h post-infection, as shown in Figure 4I and Additional file 1P. Given the discordance between NRF2 mRNA and protein expression profiles post-infection, it was hypothesized that E. coli infection might facilitate NRF2 degradation.