

Toll-like receptor 4 (TLR4) (a) and TLR9 (b) signaling. TLR4 signaling activates two pathways originating at the intracytoplasmic domain of TLR4. One is the MyD88-dependent pathway, which sequentially activates NF-κB and MAPK cascades (not shown) through IRAK and TRAF6. This pathway is crucial for cytokine production. The other is the MyD88-independent pathway, which can lead to activation of NF-κB and MAPK cascades with delayed kinetics.
Kaisho, Tsuneyasu, and Shizuo Akira. "Dendritic-cell function in Toll-like receptor-and MyD88-knockout mice." Trends in immunology 22.2 (2001): 78-83.