All of the following are Integrin molecules except____.: (A) LFA-1, (B) MAC-1, (C) VLA-4, (D) CD 31
Answer is D. Platelet endothelial cell adhesion molecule-1 (PECAM-1) (also called CD31), an adhesion molecule of the immunoglobulin (Ig) superfamily  expressed  on  leukocytes  and  endothelial  cells,  mediates the binding events needed for leukocytes to traverse the endothelium.