These results, in conjunction with the observations that signs of cellular senescence, such as the induction of both p16INK4a and SASP factor (IL-6) expression, were observed in the vicinity of the bacterial invasion within the tumour regions (Fig. 5b), strongly suggest that these two butyrate-producing bacteria are involved in the implementation of cellular senescence in human colorectal tissues. This evidence concerns the gene CDKN2A and neoplasm.