Figure 6.

Plk1^Polo inhibition dampens MT dynamicity in vivo. (A–C) Plk1^Polo inhibition decreased MT growth rate and catastrophe frequency in mitosis, but not in interphase. Mitotic astral MTs in the monopolar spindle induced by Klp61F (kinesin-5) RNAi were analyzed (100–200 comets per cell, and eight or nine cells in each condition). Each dot in the graph represents the mean value obtained from a cell. Asterisks indicate statistically significant differences (***, P < 0.0001; Turkey’s multiple comparisons test; the normality of data distribution was checked by D’Agostino–Pearson omnibus normality test and Shapiro–Wilk normality test). Error bars indicate SDs. Bar for cell images, 10 µm; horizontal bar for kymographs, 1 min; vertical bar for kymographs, 5 µm. (D) Reconstitution of regulated microtubule polymerization dynamics was achieved in this study. Three-phase polymerization cycles were observed when five factors were mixed with tubulin. Addition of the active Plk1 kinase increased MT dynamicity, wherein pausing became rare.