<prompt> All of the following are Integrin molecules except___.LFA-1MAC-1VLA-4CD 31  <response>: 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. 