Figure 2.

Toll-like receptors and IL-1 receptor family signaling pathways. ST2L (IL-33r) and IL-1r signal through the MyD88, IRAK4, and TRAF6 pathway. ST2L and IL-1r share this pathway with most TLRs. Binding of ST2L, IL-1r, and TLRs activates NF-κb, resulting in the release of inflammatory cytokines. Most TLRs signal through MyD88 expect for TLR3, which signals through the TRIF pathway. TLR4 can signal through both MyD88 and TRIF. TLR3, TLR7/TLR8, and TLR9 are expressed in the endosome while other TLRs are expressed on the cell surface. TLR1 and TLR6 recognize their ligand with TLR2 heterodimers.