Colchicine is an example of mitotic inhibitor. It is mostly used to treat gout and rheumatism. Today, this alkaloid is used in agriculture to breed plants. Colchicine inhibits cell division by disrupting the formation of microtubules which are protein fibers that make up the spindle fibers. Spindle fibers begin to assemble during the prophase stage. Thus, colchicine arrests the cell division during the prophase stage.