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: Surgery
[{'content': 'A 50-yr-old male presents with obstructive symptoms. Biopsy of stomach reveals Gastrointestinal stromal tumor (GIST). Most appropriate marker for GIST is: \nSelect and explain. \nA. CD 34, B. CD 117, C. CD 30, D. CD 10', 'role': 'user'}, {'content': 'Answer: B \nExplanation: GISTs express the Kit (CD117, stem cell factor receptor) protein. The kit is a transmembrane tyrosine kinase receptor. The Kit protein is detected by immunohistochemistry and can reliably distinguish GISTs from true smooth muscle neoplasms.\nMost GISTs also are positive for CD34, a hematopoietic progenitor cell antigen.\nKIT is used not only for diagnosis but also for targeted therapy of GISTs. Imatinib, a tyrosine kinase inhibitor, is widely used in the treatment of advanced and metastatic GISTs and has been recently employed in the neoadjuvant and adjuvant set-up with encouraging results.', 'role': 'assistant'}]