Responses of NMuMG/Fucci2 cells to etoposide analyzed using the LCV100. (A) Histogram (fraction %) of occurrence of normal cycling or G2 arrest (white), nuclear mis-segregation characterized by chromosome fragmentation (gray), tetraploid cells generated by endoreplication (black), and cell death (vertical line) at various concentrations of the drug. (B) Fluorescence images of NMuMG/Fucci2 cells treated with 0, 1, and 10 μM etoposide. In the presence of etoposide, the yellowish green nuclei predominated transiently at 12 h, suggesting cell cycle arrest at the G2/M checkpoint. Scale bars, 10 μm. (C)In the presence of 1 μM etoposide, an NMuMG/Fucci2 cell divided after a relatively long stay in G2 phase. The two daughter cells experienced different fates; one cell (labeled with an open arrowhead) underwent endoreplication (top), and the other (labeled with a solid arrowhead) underwent nuclear mis-segregation (bottom). The yellowish green-to-red color conversion is indicated by an white arrow (top). Scale bar, 10 μm.