<prompt> Rolling of leucocytes on endothelial cells is mediated by which of the following proteins?SelectinsIntegrinsTransferrinPECAM-1  <response>: Rolling interactions of leucocytes are mediated by a family of proteins called as selectins 3 types of selectins: L - selectins on leucocytes , E - selectin on endothelium , P-selectin On platelets, endothelium Integrins: Firm adhesion of leucocyte to endothelial cell is mediated by family of leucocyte surface proteins called as integrins Transferrin: Iron transpoing protein PECAM-1: platelet endothelium cell adhesion molecule: Present in the inter-cellular junction between endothelial cells Help in migration of leucocytes 