The most ancient host defense system found in mammals, insects and plants are mediated by Toll-like receptors (TLRs) and its associated signaling pathways of NK-κB. Signaling pathways of downstream of TLR2 or TLR4 complex which includes ligands (LPS or another), CD14 or/and MD-2 and receptor itself recruit MyD88 to activate the autophosphorylation of IRAK. The oligomerization of TNF receptor-associated factor 6 (TRAF6) is necessary to initiate the activation of NF-kB-inducing kinase (NIK) which finally leads to the activation of NF-κB via the Toll/IL-1-receptor homologous region(TIR) domain.