Double inactivation of motif 2 and motif 3 does not affect the ability of RANK to activate the NF-κB, JNK, p38, and ERK pathways. BMMs expressing hFas-WT or hFas-M23 were treated with α-Fas (100 ng/ml) for 0, 5, or 10 min as indicated. The activation of the NF-κB, JNK, p38, and ERK pathways was assessed as phosphorylation of IκB, JNK, p38, and ERK by Western blot analysis. BMMs expressing hFas-WT were used as a positive control.