This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Pathology
[{'content': 'Gastrointestinal stromal tumor (GIST) occur from mutation of- \nSelect and explain. \nA. c-KIT oncogene, B. c-KTT oncogene, C. c-KTT oncogene, D. c-RET oncogene', 'role': 'user'}, {'content': 'Answer: A \nExplanation: GIST is the most common mesenchymal tumor of the abdomen PATHOGENESIS Approximately 75% to 80% of all GISTs have oncogenic, gain-of-function mutations of the gene encoding the tyrosine kinase c-KIT, which is the receptor for stem cell factor. Another 8% of GISTs have mutations that activate a related tyrosine kinase, platelet-derived growth factor receptor A (PDGFRA); thus activating mutations in tyrosine kinases are found in viually all GISTs. However, either mutation is sufficient for tumorigenesis, and c-KIT and PDGFRA mutations are almost never found in a single tumor. GISTs appear to arise from, or share a common stem cell with, the interstitial cells of Cajal, which express c-KIT, are located in the muscularis propria, and serve as pacemaker cells for gut peristalsis. TEXT BOOK OF ROBBINS BASIC PAYHOLOGY NINTH EDITION PAGE.572 IMAGE REF:', 'role': 'assistant'}]