Signals from the IL-1 receptor (IL-1R)/Toll-like receptor (TLR) and TNF receptor (TNFR) superfamilies are critical for regulating the function of antigen-presenting cells. Signals transduced by these molecules lead to increased expression and activation of transcription factors such as NF-κB. TNF receptor-associated factor 6 (TRAF6) is unique in that it is a signaling adapter molecule common to both families. TRAF6 is important in cytokine production, dendritic cell (DC) maturation, and the T cell stimulatory capacity of DCs in response to TLR and CD40 ligands. It can be activated in the IL-1R/TLR signaling pathway by IL-1 receptor-associated kinase 1 (IRAK-1) or by other TLR adaptor molecules such as TRIF. Also, it has been shown that TRAF6 can interact directly with TNFR family members CD40 and RANK.