Fig. (4) Composition and signal triggered by complex I and complex II of FADD and TRADD-recruiting receptors.For the FADDrecruiting receptors (CD95 and TRAIL) as well as the TRADD-recruiting receptors (TNF and DR3), the complex defined as complex I is the protein complex which forms at the plasma membrane and exerts the primary function of the respective receptor, i.e apoptosis for CD95 and TRAIL-R1/R2 and gene induction via NF-κB and MAPK activation by TNFR-R1 and DR3. By an undetermined mechanism, the different complexes I dissociate from the DD of the respective receptor and recruit additional proteins from the cytosol and trigger the secondary function of each receptor. In the case of pro-apoptotic receptors this is gene induction via activation of NF-κB and MAPKinases pathways; in the case of the primarily immunostimulatory, pro-inflammatory receptors it is induction of apoptosis.