Fig. 5. CaM-EGFP redistribution in mitotic MDCKs under vinblastine treatment. Mitotic cells (A-G) stained for microtubules at different levels of spindle impairment (green, CaM-EGFP; red, -tubulin; blue, chromosomes; projection of deconvolved sections). (A,B) (1 hour, 0.5 nM) Stages I and II with spindle shortening and CaM in a ring-like structure at spindle poles and along spindle microtubules with decreasing intensity. (C,D) (1 hour, 1 nM) Stage III with CaM at the cores of the star-like structures. (E) (1 hour, 10 nM) Stage IV shows the CaM in a punctate distribution but immunofluorescence does not identify remaining kinetochore microtubules. (F) (1 hour, 50 nM) Stage V with striking release of the calmodulin from the punctuate accumulation in an even cytoplasmic distribution. (G) (1 hour, 100 nM) Stage VI in which tubulin forms paracrystals, with a similar cytoplasmic distribution of CaM as in stage V. (H) (1 hour, 100 nM) Interphase cells with tubulin paracrystals. (I-L) Relative distribution of CaM-EGFP (green) and kinetochores (red) with chromosomes (blue) in vinblastine-treated MDCK cells (projection of deconvolved series). (I) (10 nM, 1 hour) At the arrest of mitosis in prophase in a monopolar spindle, the CaM shows the gradient distribution along microtubules. (J, stage III and K, stage IV) (0.5 nM, 1 hour) star-like structures (details shown in insets i and ii); the distance between the kinetochores and CaM core shortens progressively (K), and the CaM along the microtubule is progressively redistributed into the cytoplasm in the stage V (L; 100 nM, 1 hour). Bar, 10 µm.