Deletion of the virulence factor polyketide synthase (Pks) genotoxic island of E. coli NC101 reduced numbers of tumors and invasion in mice, and presence of Pks+ E. coli NC101 was associated with patients with IBD and CRC, suggesting that colitis-induced dysbiosis and expansion of virulence microbes can lead to tumorigenesis [116]. This evidence concerns the gene ARAF and colitis.