The antibody against CD31 was raised in mouse using a portion of the human CD31 extracellular domain (28-315aa) as the immunogen. The antibody exists as a non-conjugated isotype IgG2a, purified by protein A with a purity greater than 95%. This antibody has been validated on ELISA, Western blot (WB), Immunohistochemistry (IHC), Immunofluorescence (IF), and Flow Cytometry (FC). Since PECAM1 or CD31 is related to pro-inflammatory processes and has related roles in angiogenesis, it can be found on carcinomas modulating the immune response. The Platelet endothelial cell adhesion molecule, PECAM1 or CD31, is a protein required for the leukocyte transendothelial migration (TEM). Also, PECAM1 controls the macrophage-mediated phagocytosis of leukocytes. This protein is present in viable leukocytes and platelets and generally concentrated between their borders with epithelial cells. PECAM1 presence makes leukocytes avoid the macrophage phagocytosis with a detachment signaling.