(A) Comparative plots of spindle length dynamics of wee1-50 (light-red, n = 20) and wee1-50klp9Δ (dark-red, n = 20) [left panel], wild-type (light-green, n = 20) and klp9Δ (dark-green, n = 20) [central panel], cdc25-22 (light-blue n = 20) and cdc25-22klp9Δ (dark-blue, n = 20) [right panel]. Bold curves correspond to mean spindle dynamics of each cell type. (B) Time-lapse image from mitosis onset until spindle breakdown of a wild-type (wt) cell expressing mCherry-Atb2 (tubulin) and Klp9-GFP. Each frame corresponds to 2 min interval. Arrowhead marks the start of anaphase B. Scale bar, 5 µm. (C) Model for anaphase spindle elongation by Klp9, based on Fu et al., 2009. Microtubules are shown in red, Klp9 in green and Ase1 in orange. (D) Comparative plot of anaphase spindle dynamics of wee1-50klp9Δ (dark-red, n = 20), klp9Δ (dark-green, n = 20) and cdc25-22klp9Δ (dark-blue, n = 20). Bold curves correspond to mean spindle dynamics. (E) Box plot comparison of anaphase B spindle elongation velocities (v) in wee1-50klp9Δ, klp9Δ and cdc25-22klp9Δ. P values were calculated by Mann-Whitney U test; data sets are defined as not significantly different (n.s.) if p>0.05. (F) Final spindle length in the klp9Δ background plotted against maximum cell length (wee1-50klp9Δ: n = 41, klp9Δ: n = 46, cdc25-22klp9Δ: n = 45). (G) Total spindle duration in the klp9Δ background plotted against cell length (wee1-50klp9Δ: n = 41, klp9Δ: n = 46, cdc25-22klp9Δ: n = 45). Data in (F–G) was fitted by linear regression (dashed lines), showing the regression coefficient R2 and the slope m. Data obtained from n cells was collected from three independent experiments.