Table 4. FCS Autocorrelation analysis of ECFP-tubulin in PTK2 cells treated with microtubule depolymerizing agents.

	No treatment	Nocodazole	S-methyl DM1	Demecolcine	Vinblastine
Molecular number	8 ± 1	17 ± 3	18 ± 3	11 ± 3	6 ± 1
Dwell time, ms	3.0 ± 0.2	3.6 ± 0.5	3.2 ± 0.2	3.0 ± 0.3	5.8 ± 0.4
Number of cells	29	12	9	9	11

Each compound was added into culture medium at the following final concentration: nocodazole (0.3 μM), S-methyl DM1 (0.2 μM), demecolcine (1.6 μM) and vinblastine (1 μM). Average molecular number (ECFP-tubulin) and average residence time (inversely related to diffusion constant) were determined by fitting time autocorrelation curves (Fig. 4A) to a 3D diffusion model (see Methods).