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: Pharmacology
[{'content': 'All of the following have receptors which are transcription factors, except: \nSelect and explain. \nA. Insulin, B. Estrogen, C. Glucocoicoids, D. Vitamin D', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Insulin receptors themselves are Enzymatic proteins and not Transcription factors. Ref: K D Tripathi Textbook of Pharmacology, 5th Edition, Pages 45, 214; Ganong Review of Medical Physiology By Barrett, Pages 320-21; Cell Physiology Source Book By Nicholas Sperelakis, Pages 657-58', 'role': 'assistant'}]