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: Physiology
[{'content': 'Function of phospholamban is \nSelect and explain. \nA. Regulates Na+K+, B. Transports calcium out of mitochondria, C. Collects calcium into sarcoplasmic reticulum, D. Binds actin with myosin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Phospholamban increases the activity of SERCA\n↓\nIt causes accumulation of Ca2+\xa0by sarcoplasmic reticulum\n↓\nIt leads to Lusiotropic effect, Increase in rate of relaxation', 'role': 'assistant'}]