Table 1.

Microtubule depolymerization rates after spindle cutting

Treatment	Polarization microscopy	Fluorescence microscopy
Spindle cut alone	32.3 ± 5.1 (39)	28.1 ± 6.5 (19)
Spindle cut + hexylene glycol	No depolymerization (n = 6)
Spindle cut + DMSO	24.1 ± 3.3 (10)
Spindle cut + α-MCAK	32.0 ± 6.4 (21)
Spindle cut + AMPPNP	30.1 ± 4.3 (9)
Aster cut + α-MCAK	39.5 ± 5.3 (15)

CSF (cytostatic factor) arrested Xenopus egg extract spindles or asters were cut with paired microneedles and imaged by time-lapse polarization or fluorescence microscopy. Where indicated, extracts were preincubated with antibody to MCAK at a final concentration of 150 μg/ml, DMSO at a final dilution to 2%, AMPPNP at a final concentration of 5 mM, or hexylene glycol at a final dilution to 2%. Rates are given ± SD. The number of cut half spindles or asters measured is in parentheses.