(A) The membrane fraction from control or MG132-treated HCT116 cells was subjected to immunoblot assay with antibodies against Bax or VDAC, a mitochondrial outer membrane protein. The result suggests that MG132 induces Bax translocation to the mitochondria. (B) HCT 116 cells expressing GFP-Bax were treated with MG132 and stained with Hoechst 33342. Long arrows denote cells with punctated GFP-Bax signals while short arrows denote the apoptotic nuclei. The result indicates a well correlated Bax translocation and apoptosis in the cells. (C) Cells treated as in (B) were counter-stained with MitoTracker Red. The result indicates that the punctated GFP-Bax signal is colocalized with that of mitochondria. (D) Time-dependent Bax translocation following the treatment with MG132 as indicated by the increases in cells with punctated GFP-Bax signals. For details, see Ding et al. in this issue.