These data indicate that, although umbrella cells are clearly the frontline in urothelial defenses against the T1F-UPEC, the lower cell layers possess the necessary signaling cascade for NF-κB activation and can be involved, perhaps in a “backup” role, in the inflammatory responses at a later infection stage and/or during the “on-phase” of the type 1 fimbriae (Fig. 7C). Here, NFKB1 is linked to infection.