TLR4 and colorectal carcinoma: In CRC, Fn infection can activate the toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/NF-κB signaling pathway, upregulate IL-17F, IL-21, IL-22 and macrophage inflammatory protein-3 alpha (MIP-3a) to promote tumor cell proliferation (Figure 5) (Yang et al., 2017).