Explanation of why two different drugs are toxic to dividing cells in regards to microtubule dynamics.

The drug taxol, extracted from the bark of yew trees, has the opposite effect of the drug colchicine, an alkaloid from autumn crocus. Taxol binds tightly to microtubules and stabilizes them. When taxol is added to cells, it causes much of the free tubulin to assemble into microtubules. In contrast, colchicine prevents microtubule formation. Taxol is just as disruptive to dividing cells as colchicine, and both are used as anticancer drugs. Based on your knowledge of microtuble dynamics, suggest why both drugs are toxic to dividing cells despite their opposite actions.

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...f the process, most of the tubulin in the cytosol is in free form. The two centrosomes at the poles of the cell initiate microtubule assembly, causing the tubulin to assemble in an organized manner into spindles which extend towards the centre of the cell and eventually meet at the metaphase plate where the chromosomes assemble. The spindle then mediates sister chromatid segregation during anaphase. As mitosis nears completion, the microtubules are disassembled so that cytokinesis (partitioning of the cytoplasm into the two separate daughter cells and cleavage) can occur. ...