The nucleotide-binding oligomerization domain-like receptors, in short NOD-like receptors (NLRs) are intracellular sensors of PAMPs that enter the cell via phagocytosis or pores and DAMPs that are associated with cell stress. They are part of pattern recognition receptors and play key roles in regulation of innate immune response. NLRs can cooperate with Toll-like receptors and regulate inflammatory and apoptotic response. They are found in lymphocytes, macrophages, dendritic cells and also in nonimmune cells, for example in epithelium. NLRs are highly conserved through evolution. Their homologs have been discovered in many different animal species (APAF1) and also in the plant kingdom (disease-resistance R protein).