This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
[{'content': 'Which of the following does not act as a second messenger \nSelect and explain. \nA. Cyclic AMP, B. Inositol triphosphate, C. Diacycglycerol, D. G protein', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref-KDT 6/e p48 Cyclic AMP,IP3 and DAG a second messenger where does G proteins are first messengers.IP3 and DAG increases the release of Ca+2 that acts as a third messenger', 'role': 'assistant'}]