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. 2009 Nov 17;101(2):313–320. doi: 10.1111/j.1349-7006.2009.01442.x

Figure 1.

Figure 1

 MyD88 and Toll‐interleukin I receptor‐domain (TIR)‐containing adoptor molecule (TICAM‐1) pathways. MyD88 is an adaptor for all Toll‐like receptors (TLR), except TLR3 (a). TLR2 and TLR4 recruit MyD88 via the bridging adaptor Toll‐interleukin I receptor‐domain (TIR)‐containing adoptor protein (TIRAP) (MAL) (b). Other TLR directly recruit MyD88. MyD88 activates nuclear factor‐kappa β (NF‐κB) in most cell types, except plasmacytoid dendritic cells (pDC), which activate the interferan‐regulatory factor (IRF‐7) transcription factor. MyD88 pathway is involved in the production of pro‐inflammatory cytokines in most cells. In contrast, the MyD88 pathway in pDC and the TICAM‐1 pathway in myeloid dendritic cells (DC) activate the type interferon (IFN) promoter via IRF‐3 or IRF‐7 (b). TLR4 can recruit both MyD88 and TICAM‐1, whereas other TLR recruit either of them. Each TLR responds to different agonistic stimuli, as shown in Table 1. DC, dendritic cells; IFN, interferon; IRF, interferon‐regulatory factor; pDC, plasmacytoid DC; TICAM‐1, Toll‐interleukin 1 receptor domain (TIR)‐containing adaptor molecule; TIRAP, Toll‐interleukin 1 receptor (TIR) domain‐containing adapter protein; TLR, toll like receptor.