All of the following are Integrin molecules except____.
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.
LFA-1
MAC-1
VLA-4
CD 31