ARAF and cancer: Colibactin is also produced in the gut by pks+ E. coli and inflicts DNA damage in intestinal epithelial cells.17–19.This DNA damage can ultimately lead to gene mutagenesis, and colibactin is suspected of promoting colon cancer.2,17,18 In mouse models that recapitulate intestinal tumorigenesis, inflammation is essential for cancer promotion by pks+ E. coli, and inflammation increases the transcription of pks-encoded genes.18,20,21 Thus, these bacteria appear to promote cancer under specific environmental conditions that favor expression of colibactin.