Persistent Plk1 activity at kinetochores suppresses microtubule dynamics. (A) Cells expressing PA-GFP-tubulin together with either Hec1 or Hec1-Plk1^T210D were imaged live before and after photoactivation of a spot near the metaphase plate at t = 0. Images show PA-GFP-tubulin or Hec1 or Hec1-Plk1^T210D visualized with mCherry. (B) GFP intensity in the activated spot (white circles in A) was calculated at each time point as the intensity relative to the initial value after activation. The relative GFP intensities were corrected for photobleaching based on a taxol control, averaged over multiple cells (n ≥ 8), and fit with double-exponential decay curves. AU, arbitrary unit. (C) Curve-fitting parameters K_f and K_s represent the fast and slow time constants, respectively.