TLR2 and rectal cancer: Streptococcus belongs to Pachylobacteria, which is a common pathogen in the body, and studies have suggested that it may be a transitional bacterium in the course from colitis to rectal cancer and exerts an injurious effect by activating inflammatory factors (e.g., NF-κB, TNF-α, IL-1, and COX-2) and the immune molecule, TLR2 [39,40].