Figure 8.

The APC is not required for the mitotic dissociation of cohesins from chromatin. (A) CDC27 immunoblot showing Xenopus interphase extract before and after depletion with either control or CDC27 antibodies. (B) APC-depleted (left) and control-depleted (right) Xenopus interphase extracts were incubated with sperm nuclei for 30 min and then nondegradable cyclin B Δ90 was added to trigger entry into mitosis. At different time points either extract samples (top) or chromatin reisolated from the reaction mixture by sucrose cushion centrifugation (bottom) were analyzed by SDS-PAGE and either PhosphorImaging (S³⁵CDC25) or immunoblotting with antibodies to the indicated proteins (all other panels). The cell cycle state of the extracts was analyzed by monitoring the behavior of ³⁵S-labeled CDC25 and of endogenous cyclin B. Data from two different experiments are shown. In experiment 2, the degree of APC depletion and the cell cycle behavior of the extracts were the same as in experiment 1 (data not shown).