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: Pathology
[{'content': 'A 56 year old chronic smoker, mass in bronchus resected. What is the possible marker? \nSelect and explain. \nA. Cytokeratin, B. Vimentin, C. Epithelial membrane Cadherin, D. Leukocyte', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Cytokeratin o Squamous cell carcinoma is most commonly found in men and is closely correlated with a smoking history. o Histologically, it is characterized by keratinization and intracellular bridges. o Cytokeratin is a marker for keratinizing cells.", 'role': 'assistant'}]