TLR4 and colorectal carcinoma: Thus, we speculated that Fn infection may facilitate CRC malignancy involving Mφ activation, either directly or indirectly, via activating specific signal pathways such as that of TLR4-dependent NF-κB. Now we have shown that PAMP extracted from Fn and Fn itself could be recognized by TLR4, which further activates its downstream signaling cascade in CRC (8, 21).