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
[{'content': 'Most important for diapedesis \nSelect and explain. \nA. PECAM, B. Selectin, C. Integrin, D. Mucin like Glycoprotein', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Diapedesis or Transmigration-process of leukocyte recruitment is migration of the leukocytes through the endothelium.\n\nMost important for diapedesis is PECAM- 1 and CD31 molecules', 'role': 'assistant'}]