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': 'Commonest mutations that are associated with GIST are in \nSelect and explain. \nA. Platelet-derived growth factor receptor a, B. Tyrosine kinase KIT, C. BRAF, D. NRAS', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Approximately 75% to 80% of all GISTs have oncogenic, gain-of-function mutations in the receptor tyrosine kinase KIT. (C-KIT or CD 117)Approximately 8% of GISTs have mutations that activate a closely related receptor tyrosine kinase, platelet-derived growth factor receptor a (PDGFRA).Some GISTs without mutated KIT or PDGFRA have mutations in other genes that function in these pathways (NF1, BRAF, HRAS, or NRAS).Ref: Robbins Pathology; 9th edition; Page no: 775', 'role': 'assistant'}]