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. 2012 May 22;3:138. doi: 10.3389/fphys.2012.00138

Figure 1.

Figure 1

The overview of TLR signaling. TLR1, TLR2, TLR4, TLR5, and TLR6 are expressed on cell membrane. TLR3, TLR7/8, and TLR9 are expressed in endosome. All TLRs, expect for TLR3, activate MyD88-dependent pathway to induce NF-κB and p38/JNK activation. TLR2 and TLR4 signaling require TIRAP and MyD88. TLR3 requires IRIF to activate TBK1/IKKε. Subsequent to TLR4 internalization, TLR4 signaling activates TRAM/TRIF-dependent pathway. TLR3/4-dependent TRIF-dependent signaling induces IRF3 activation and IFN-β production. TLR7/8 and TLR9 induce IFN-α production through IRF7.