This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Microtubule formation is inhibited by: 
Select and explain. 
A. Taxol, B. Vincristine, C. Etoposide, D. Irinotectan
B: Vincristine
Answer: B: Vincristine 
Explanation: Vincristine