TTBK2 regulates MT dynamics via KIF2A. (A) Time series of MT dynamics in HeLa cells. HeLa cells expressing EMTB-2xEGFP were transfected with the indicated siRNAs, and MT dynamics were monitored. The white and yellow arrowheads indicate static MT ends and MT ends undergoing rapid depolymerization at the cell edge, respectively. The time is given in seconds. Bars, 5 µm. (B) Life history plots of representative MTs in control (blue), TTBK2-depleted (red), KIF2A-depleted (yellow), and TTBK2- and KIF2A-depleted cells (green). TTBK2 depletion shortened the lifetime of the MTs, and these MTs underwent continuous depolymerization. (C) Quantification of the parameters of MT dynamics. Four parameters (growth rate, shrink rate, catastrophe frequency, and rescue frequency) were measured for a total of ≥50 MTs in >10 cells for each condition. TTBK2 depletion significantly increased the shrink rate and decreased the rescue frequency. Error bars indicate the SD. ***, P < 0.001 (one-way ANOVA, Tukey’s HSD). All of the results are representative of more than four independent experiments. Also see Videos 3–6.