FASLG and lupus nephritis: As MRL-lpr mice bear a mutation in the gene encoding Fas and are therefore not able to induce apoptotic cell death via the Fas/FasL pathway, which also targets caspase-3, the number of TUNEL+ cells and cleaved caspase-3+ cells were reduced in the kidneys of MRL-lpr mice compared to MRL mice (Supplemental Figure S7C,D), suggesting that apart from GzmB-induced cell death the Fas/FasL pathway also contributes to induction of apoptosis in lupus nephritis.