Confocal analysis and cell sorting quantification of DLD-1 (A,B), DLD1/Tet-On-gef (C,D), DLD1/Tet-On-apoptin (E,F), and DLD1/Tet-On-gef-apoptin (G,H) cells (Scale bar = 50 μm). Cells were stained with annexin V-FITC and PI. Early apoptosis (Q4: green stain for annexin-FITC), late apoptosis (Q2: green stain for annexin-FITC in combination with red stain for PI), and necrosis (Q1: red stain for PI) can be observed; viable cells are not visible (Q3). In DLD1 expressing gef or apoptin, cells in early and late apoptosis are observed (C,E). DLD1/Tet-On-gef-apoptin cells showed a higher proportion of necrotic cells when compared to some early and late apoptotic cells (G,H).