Sentin recruitment to the tip restores spindle length and microtubule dynamics. (A) The short spindle phenotype was not rescued by localization-deficient Sentin (1–950 aa) but was rescued by the plus end–tracking Sentin (1–950 aa)-hAPCc (2,744–2,843 aa) fusion gene (± SEM; n = 13–25). (B) Plus end–tracking ability was recovered when hAPCc was attached to GFP-Sentin (1–940 aa). Time spent in pause was also reduced by the hAPCc attachment (72 to 30%; n = 30). GFP is shown in green. mCherry-tubulin is shown in red. Bar, 10 µm. (C) A fusion construct in which the cargo-binding domain of EB1 (263–292 aa) is replaced by full-length Sentin-GFP. (D) EBN-Sentin-GFP and mRFP-CLASP (containing the SxIP motif) were cotransfected. EBN-Sentin-GFP, but not mRFP-CLASP, showed plus end–tracking when endogenous EB1 and Sentin were depleted, suggesting that EBN-Sentin-GFP could not interact with the SxIP motif. Also see Video 5 (another control hAPCc is also displayed). Bar, 2 µm. (E) The fusion construct EBN-Sentin-GFP, but not EB1-GFP or EBN-GFP, rescued the short spindle phenotype produced by double EB1–Sentin RNAi (± SEM; n = 21–26). Also see Table III and Video 5 for the interphase dynamics recovery.