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: Pathology
Which is the most important adhesion molecule for diapedesis? 
Select and explain. 
A. CD34, B. CD 31, C. P-selection, D. E-selection
B: CD 31
Answer: B: CD 31 
Explanation: CD 31 (PECAM-1) (Platelet endothelial cells adhesion molecule) - It is most important adhesion molecule for Diapedesis. It helps in leukocyte migration through endothelium.