For example, Nod-like receptors (NLRs) are a PRRs subfamily located on the cell membrane, which can activate a series of defensive mechanisms to fight against invasive bacteria.[77] The protective effect of NOD1 is mainly through the barrier preventing the transition from inflammation to carcinogenesis.[78] NOD2 also plays an important role in the regulation of microbial flora and reduces susceptibility to colorectal cancer. This evidence concerns the gene NOD2 and colorectal cancer.