Fig. 4.

Nontransformed RPE-1 cells show higher survival rates when dividing in the presence of nocodazole or taxol than U2OS or HeLa cells. Phase-contrast recordings of RPE-1, U2OS and HeLa cultures incubated with nocodazole (a) or taxol (b) were scored (cf. Fig. 2) for cells that died in mitosis (red), died within 10 h of escaping mitosis (light green), or survived ≥10 h after escaping mitosis (dark green). Numbers in the white box within each subset of an experimental treatment note the percentage of cells in that subset. (a) RPE-1, U2OS and HeLa cells treated with nocodazole alone (lanes 1, 3, and 5) or nocodazole and Q-VD-OPh (a caspase inhibitor; lanes 2, 4, and 6). Concentrations and total cell number are indicated above each column. Note that relative to RPE-1 cells, nocodazole concentrations that inhibit spindle MT assembly kill substantially more U2OS and HeLa cells during or shortly after mitosis. (b) RPE-1, U2OS and HeLa cultures treated with either 5 nM (lanes 1, 3, and 5) or 500 nM (lanes 2, 4, and 6) taxol. As for nocodazole, compared to RPE-1 cells U2OS and HeLa have a more difficult time surviving mitosis in the presence of taxol. Note also that taxol kills substantially fewer U2OS than HeLa cells during or after mitosis, and that only 7% of HeLa cells dividing in 5 nM taxol are alive 10 h later.