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
Mechanism of action of paclitaxel is ? 
Select and explain. 
A. Topoisomerase inhibition, B. Increase the polymerization of tubulin, C. Inhibition of protein synthesis, D. Alkylation of DNA
B: Increase the polymerization of tubulin
Answer: B: Increase the polymerization of tubulin 
Explanation: Ans. is 'b' i.e., Increase the polymerization of tubulin Taxanes Paclitaxel and docetaxel function as a mitotic spindle poison through high affinity binding to microtubules with enhancement of tubulin polymerization. The microtubules are stabilized and their depolymerization is prevented - inhibition of mitosis and cell division. Paclitaxel is metabolized in liver and undergoes enterohepatic circulation - dose should be reduced in liver dysfunction. Paclitaxel can cause hypersensivity reaction which does not occur with a novel albumin-bound paclitaxel preparation. Paclitaxel and docetaxel both can cause bone marrow depression & peripheral neuropathy.