This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Ophthalmology
Universal marker of limbal stem cells- 
Select and explain. 
A. Elastin, B. Keratin, C. ABCG2, D. Collagen
C: ABCG2
Answer: C: ABCG2 
Explanation: *Universal marker of limbal stem cells is ABCG2 Ref:Human Adult Stem Cells edited by John Masters, Bernhard Palsson p.117