Deletion of FADD enhances LPS- and IL-1β–induced degradation of IκB. FADD+/+ and FADD–/– MEFs were incubated with medium, LPS (100 ng/ml), or IL-1β (10 ng/ml) for increasing exposure times, and lysates derived from these cells were immunoblotted with antibodies raised against either IκB-α or IκB-β (a and b). In other experiments, FADD+/+ MEFs stably expressing GFP (+/+ GFP) or FADD–/– MEFs stably expressing either GFP (–/– GFP) or FADD (–/– + FADD) were treated with LPS (100 ng/ml) or IL-1β (10 ng/ml) for 45 minutes, and lysates were immunoblotted as above (c).