This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Peptic Ulcer Disease, Subject name: Pathology
[{'content': 'Which of the following markers is not typically expressed by neuroendocrine tumours? \nSelect and explain. \nA. Synaptophysin, B. Chromogranin, C. CD56, D. CK7', 'role': 'user'}, {'content': 'Answer: D \nExplanation: CK7 is an epithelial cell marker and is positive in carcinomas (especially the epithelial tumours arising from foregut). The following immunohistochemical markers are positive in neuroendocrine neoplasms: Synaptophysin Chromogranin A CD56 Neuron specific enolase (NSE)', 'role': 'assistant'}]