Difference in the kinetics of caspase activity between the C- and D-type apoptotic cells. Cell-tracking analysis revealed differential kinetics of caspase activity between the C- and D-type cells. (A–C) Ratio-tracking analysis. Each line corresponds to a single cell. (A) In C-type cells (n = 14), the V/C dropped rapidly within 10 min. The x’s mark the time when the C-type cell underwent cell fragmentation. (B and C) In D-type cells (n = 9), the V/C decreased more slowly than in C-type cells, continuing to decline for an additional ∼20 min, and then plateaued. Long-term tracking results are shown in C. The D-type cells did not undergo cell fragmentation during live imaging. The black circle shows the time when the cell could not be tracked anymore as a result of being lost or out of focus. (D) Time to reach the bottom values of V/C. In D-type cells, decline of V/C was significantly slower than in C-type cells. Each square represents individual cells, and its colors correspond to those of A and B. The bottom V/C values of D-type cells were defined as the point at which the V/C reached to the plateau values (see Materials and methods). Black bars indicate mean values (C-type cells: 8.0 ± 3.2 min; D-type cells: 16.0 ± 5.6 min; ***, P < 0.005).