Most important for diapedesis: (A) PECAM, (B) Selectin, (C) Integrin, (D) Mucin like Glycoprotein
Answer is A. Diapedesis or Transmigration-process of leukocyte recruitment is migration of the leukocytes through the endothelium.

Most important for diapedesis is PECAM- 1 and CD31 molecules