Fig. 6. (A-E) CaM-EGFP redistribution at the paclitaxel-induced microtubule polar structures in mitotic MDCKs (4 hours, 10 nM) (green, CaM-EGFP; red, -tubulin; blue, chromosomes); (A) Monopolar spindle; (B) Bipolar spindle; (C) Three-polar spindle; (D) Quadri-polar spindle; (E) Multipolar spindle; Calmodulin redistributes in a ring-like shape at the paclitaxel-induced multipolar spindle without an accumulation at the kinetochores level. CaM-preserves the ring-like shape as seen in projection at every pole. Note that in the bipolar structure the CaM content at the two poles (B) is symmetrically distributed, and at the three (C) and four poles (D) its content decreases with the increasing number of poles. (F-I) Example of steps in the paclitaxel-induced multipolar structure as shown by CaM-EGFP at polar level (green, CaM-EGFP; red, kinetochore; blue, chromosomes). The CaM-containing ring-like structure divides (A,B), producing two or more poles (C,D). The kinetochores decorate chromosomes at the metaphase plate and those that were removed together with the related microtubules; projection of deconvolved series. Bar, 10 µm.