(2014). In summary, the authors elegantly describe the interplay in the development of intestinal neoplasms in mice. Using interesting experimental tools such as transgenic mice, and simple but insightful strategies such as broad-spectrum antibiotics treatment, the authors demonstrate a clear relationship between bacteria ˘ˇˆ ˘˙the results from Lira´s group provide experimental evidence clearly in line with ‘old’ suggestions that bacteria ‘might produce carcinogens’