This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Cancer, Subject name: Pharmacology
[{'content': 'Vinca alkaloids act on: \nSelect and explain. \nA. G phase, B. S phase, C. Mitotic spindle, D. M phase', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C. Mitotic spindleVinca alkaloids are mitotic inhibitors. They disrupt the polymerization of microtubules. They inhibit the chromosomes to move apart and there is metaphase arrest. They are cell cycle specific and act on mitotic spindle.', 'role': 'assistant'}]