Premature targeting of Ipl1/Aurora activity to the spindle midzone slows anaphase spindle elongation. (A) sli15-17A reduces the anaphase B spindle elongation rate. Box plot showing rates of fast and slow spindle elongation (phases 1 and 2) in SLI15 and sli15-17A cells. (B) sli15-17A increases anaphase B phase 1 and 2 durations. Box plot showing durations of phases 1 and 2 in SLI15 and sli15-17A cells. (C) sli15-17A increases total anaphase B duration. Box plot showing anaphase B durations in SLI15 and sli15-17A cells. (D) sli15-17A does not significantly affect final anaphase spindle length. Box plot showing anaphase spindle lengths just before spindle breakdown in SLI15 and sli15-17A cells. (E) sli15-17A reduces Bim1/EB1 association with the anaphase spindle. Box plot showing mean Bim1-4GFP fluorescence intensities along anaphase spindles in cells containing sli15-17A or SLI15, BIM1-4GFP, and mCherry-TUB1. The distributions’ medians differed significantly (Mann-Whitney U test = 27613141, n_WT = 1858, n_17A = 2013, P < 2.2 × 10⁻¹⁶, two-tailed test; ρ = 0.74). See Materials and methods. ‡, P values determined using the Mann-Whitney U test for the null hypothesis that ρ = 0.5. Bim1-4GFP sizes and expression levels were comparable (see Fig. S2 D).