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
Immuno-marker for GIST is? 
Select and explain. 
A. CD 117, B. CD 4, C. CD 100, D. CD45
A: CD 117
Answer: A: CD 117 
Explanation: Ans. is 'a' i.e., CD 117 * CD 117 (c kit) is considered the most specific marker of GIST.* Other markers are CD 34, smooth muscle actin and vimentin.