Fig. 5. Induction of apoptosis by Nbk is entirely Bax dependent in HCT116 cells. HCT116 Bax wild-type (WT) and HCT116 Bax knock-out (k.o.) cells were transduced with Ad5-myc-Nbk-tTA and cultured for 24 h in the presence (Tet-off condition) or absence of doxycyclin (Tet-on condition). (A) Morphology of HCT116 cells. (B) Western blot analyses of Nbk, Bax, Bak expression, PARP and procaspase-9 cleavage. (C) Breakdown of the mitochondrial membrane potential. Loss of Δψ_m was measured on the single-cell level by the use of the cationic dye JC-1. Means ± SD were calculated from three independent experiments. (D) Apoptosis induction by Nbk. Genomic DNA fragmentation was measured on a single-cell level by determination of cells with a hypodiploid DNA content. Means ± SD were calculated from three independent experiments.