Mammalian myeloid differentiation factor 88 (MyD88) is Toll/interleukin (IL)-1 (TIR)-domain containing adapter protein which plays crucial role in TLR signaling. All TLRs, with only one exception of TLR3, can initiate downstream signaling trough MyD88. In the MyD88 - dependent pathway, once the adaptor is bound to TLR it leads to recruitment of IL1 receptor associated kinase family IRAK which is followed by activation of tumour necrosis factor receptor-associated factor 6 (TRAF6) . TRAF6 is an ubiquitin E3 ligase which in turn induces TGF-beta activating kinase 1 (TAK1) auto phosphorylation. Once activated TAK1 can ultimately mediate the induction of the transcription factor NF-kB or the mitogen-activated protein kinases (MAPK), such as JNK, p38 and ERK. This results in the translocation of the activated NF-kB and MAPKs to the nucleus and the initiation of appropriate gene transcription leading to the production of many proinflammatory cytokines and antimicrobial peptides.