This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
[{'content': 'Following monoclonal antibody is directed against alpha 4 integrin (REPEAT) \nSelect and explain. \nA. Efalizumab, B. Natalizumab, C. Ibalizumab, D. Toclizumab', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Natalizumab is anti-integrin monoclonal antibody used in ulcerative colitis, Crohn&;s disease and multiple sclerosis.Ref: Katzung 13th ed.pg 962.', 'role': 'assistant'}]