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: Biochemistry
[{'content': 'Which amino acid released from muscles is an impoant substrate for gluconeogenesis? \nSelect and explain. \nA. Alanine, B. Serine, C. Arginine, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: In the fasting state, there is a considerable output of alanine from skeletal muscle, far in excess of its concentration in the muscle proteins that are being catabolized. It is formed by transamination of pyruvate produced by glycolysis of muscle is a substrate for gluconeogenesis by the glucose-alanine cycle Ref: Harper 28th edition, chapter 20.', 'role': 'assistant'}]