FASLG and diabetes mellitus: The ability of FasL-neutralizing mAb to prevent diabetes development in NOD-wt mice without causing lymphoproliferation or autoantibody production (Su et al., 2000; Nakayama et al., 2002; Mohamood et al., 2007; Figure 4) is consistent with the existence of a large functional window to safely downregulate FasL activity for therapeutic purposes.