PP2A–B56γ and -ε contribute to central spindle length control. (A) HeLa EGFP-tubulin mCherry-histone H2B cells were treated with control or combined PP2A–B56γ and -ε siRNA for 36 h, arrested with 2 mM thymidine for 18 h, and then released for 8 h into fresh medium before imaging every minute as the cells passed through mitosis and cytokinesis. Red and green lines mark the anaphase A–B transition and onset of furrowing, respectively. (B) Central spindle length is plotted as a function of time (means ± SEM, n = 8). (C) HeLa cells were treated with control, combined PP2A–B56γ and -ε, PP2A–B56α, -γ, or -ε siRNA for 36 h, arrested with 2 mM thymidine for 18 h, and then released into fresh medium. After 10 h, these cells were stained for DNA, mouse anti-Plk1, and rabbit anti-PRC1 pT602. Central spindle length in anaphase cells is shown (means ± SEM, n = 6).