For example, the opportunistic pathogen Klebsiella pneumoniae (K. pneumoniae) can also carry pks genes as part of a mobile genetic element also encoding yersiniabactin, and these genes are observed more frequently in hypervirulent strains.115,116 Moreover, these bacteria frequently colonize the gut during early life when the colibactin-associated mutational signature is thought to be acquired in colonic epithelial cells.46 Accordingly, a neonatal K. pneumoniae isolate promoted tumor formation in ApcMin/+;IL-10−/− mice, although this phenotype was still observed in pks-deficient K. pneumoniae. Here, ARAF is linked to neoplasm.