This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'Which is not a RBC membrane protein? \nSelect and explain. \nA. Ankyrin, B. Nebulin, C. Spectrin, D. Gycophorin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The protein skeleton consists of 2D mesh of spectrin tetramers and oligomers. It is attached to RBC membrane by attaching to ankyrin. Membrane proteins like glycophorin also present. Ref: Textbook of medical physiology by N Geetha, 3rd edition, page no. 77', 'role': 'assistant'}]