NK cells from IκBα°ϵ° chimeras have normal mitochondrial membrane potential but overexpress Bcl-2. (Left) Assessment of mitochondrial membrane potential using DIOC₆ staining of splenic NK cells in WT (shaded histogram) and IκBα°ϵ° (bold line) chimeras. (Right) Bcl-2 expression on splenic NK cells from WT (shaded histograms) and IκBα°ϵ° (bold line) chimeras. Dotted line shows staining with isotype control antibody.