Fig. 1. GSK-3 interacts with spindle microtubules during mitosis. (A) A microtubule co-sedimentation assay using cycling or mitotic HeLa cell extracts. S, high speed supernatant; P, microtubule pellet; -/+ indicates the absence or presence of taxol in the assay; U, unsynchronised cells; M, Mitotic cells. Western blots were probed with antibodies against GSK-3ß. (B) HeLa cells permeabilised with 0.5% Triton before fixation with 4% paraformaldehyde and stained with affinity purified antibodies raised against GSK-3. Bar, 10 µm.