In association with beta-2 integrin heterodimer ITGAM/CD11b and ITGB2/CD18, mediates activation of TNF-alpha primed neutrophils including degranulation and superoxide production (By similarity). In addition, by preventing beta-2 integrin internalization and attenuating chemokine signaling favors adhesion over migration (By similarity). Heterophilic interaction with PECAM1 on endothelial cells plays a role in neutrophil transendothelial migration in vitro (By similarity). However, appears to be dispensable for neutrophil recruitment caused by bacterial infection in vivo (PubMed:25359465). Acts as a receptor for the mature form of protease PRTN3 allowing its display at the cell surface of neutrophils (By similarity). By displaying PRTN3 at the neutrophil cell surface, may play a role in enhancing endothelial cell junctional integrity and thus vascular integrity during neutrophil diapedesis (By similarity). Found in a complex with integrin ITGAM/CD11b and ITGB2/CD18. Interacts with PECAM1 (via Ig-like C2-type domain 6); the interaction is Ca(2+)-dependent; the interaction is direct. Interacts with serine protease PRTN3/myeloblastin; the interaction tethers PRTN3 to the cell surface; the interaction is direct. Expressed in neutrophils. Mice are viable, fertile and are born at the expected Mendelian rate. Slight decrease in blood CD11b(+)Ly-6G(-)Ly-6C(+) monocyte and CD11b(+)Ly-6G(+)Ly-6C(+) neutrophil populations. Lymphocyte and myeloid development is not affected. In S.aureus-mediated skin infection, recruitment of neutrophils and monocytes to the infection site is transiently reduced. In thioglycolate-induced peritonitis, recruitment of neutrophils is normal.