The apoptosis in NHD13 progenitors is not mediated by the death receptor pathway. (A) Proportions of annexin-V–positive LKS cells assessed by FACS (n = 3 of each geneotype). (B) CFU-GM and (C) BFU-E numbers in WT and NHD13 BM on WT, FasL^gld/gld or TNF^−/− backgrounds (n = 3 of each genotype). (D) Western blot showing the presence of native and cleaved (active) caspase 8 in WT LK cells, NHD13 LK cells, WT thymocytes treated with or without FasL. Actin is shown as a loading control. All experiments performed using 3-month-old mice. Error bars represent the SEM (*P < .05; ***P < .001).