It will be particularly interesting to determine whether Fas-mediated apoptosis is mediating cytotoxicity of diabetogenic CD8 T cells, which has recently been implicated in killing β-cells in T1D patients (Bulek et al., 2012; Coppieters et al., 2012) or involved in killing regulatory cells responsible for protecting the pancreas from autoreactive T cells. Here, FAS is linked to type 1 diabetes mellitus.