To definitely assess the role of FasL in the mechanisms underlying pemphigus, we injected PVIgG into two different gene-targeted mutant mice that selectively lack either the secreted soluble FasL (sFasL), FasLΔs/Δs mice, or the membrane-bound FasL (mFasL), FasLΔm/Δm mice (12). Here, FASLG is linked to pemphigus.