Biologically active BFT is necessary for enhancing colonic tumorigenesis in the AOM/DSS model. BALB/c mice were infected with WT-ETBF (bft-2), rETBF (bft-2) or rNTBF (bft-2 H352Y) and subjected to the standard ETBF/AOM/DSS (2%) protocol for 12 weeks. +E2, WT-ETBF (bft-2) + AOM/DSS; +rE2, rETBF (bft-2) + AOM/DSS; rN2 (bft-2 H352Y) + AOM/DSS; A/D, AOM/DSS alone. (A) Representative gross macroscopic image of the colon. White arrows indicate polyps. (B) Polyp number. S, sham control. (C) Polyp size distribution. (D) Spleen weight. (E) Colon length. Each dot represents one mouse (n = 9-12 mice per group). Horizontal bar, median. *P < 0.05, **P < 0.01, ***P < 0.001. ns, no statistical significance.