Figure 4
Cell cycle dependency of the apoptosis execution in HeLa.S-Fucci cells treated with the agonistic anti-Fas antibody or etoposide. (a) The criteria for the classification of apoptotic HeLa.S-Fucci cells into each cell cycle phase. The shrunk cells with mKO2 were at G1 phase, the shrunk cells with both mKO2 and mAG1 were at the border of G1 and S phases, the shrunk cells with mAG1 were at S, G2, and M phases, and the shrunk cells with neither mKO2 nor mAG1 were at the transition from M to G1 phases. HeLa.S-Fucci cells were cultured in the presence of 0.5 μg/ml of the agonistic anti-Fas antibody (b) or 50 μM etoposide (VP-16) (c) for 24 h, and were observed with the time-lapse fluorescence microscope at 15-min intervals. Apoptotic cells were morphologically judged on the photographs and the movies, and were counted and classified into each cell cycle phase according to the criteria as shown in panel a. At least 100 cells were counted for each measurement in all experiments. The data (mean±S.D.) were obtained from at least three independent experiments
