In low concentrations of MT poisons or stabilizers, RPE-1 cells form aberrant spindles that segregate chromosomes into two or more daughter cells. Each row depicts a cell entering (second frame) and exiting (third frame) mitosis in either 50 nM nocodazole (A), 5 nM vinblastine (B), or 5 nM taxol (C). The split-screen fluorescence images at the end of each row depict the distribution of chromosomes (DNA) and MTs in cells fixed during spindle assembly (fifth frame) and telophase/cytokinesis (sixth). Time from addition of drug to the medium is in minutes. Arrows note the cell of interest. Bars: (IMF images) 5 μm; (phase images) 20 μm.