Homophilic transmembrane adhesion molecule involved in various processes such as inflammation, cell death, axonal growth, cell chemotaxis and angiogenesis (PubMed:19557008, PubMed:24347169, PubMed:24917672, PubMed:31526566, PubMed:33472215). Promotes cell adhesion by mediating homophilic interactions via its extracellular N-terminal adhesion motif (N-NAM) (PubMed:24917672, PubMed:30510259). Involved in the progression of the inflammatory stress by promoting cell-to-cell interactions between immune cells and endothelial cells (PubMed:24917672, PubMed:30510259). Involved in leukocyte migration during inflammation by promoting transendothelial migration of macrophages via homotypic binding (PubMed:24917672). Promotes the migration of monocytes across the brain endothelium to central nervous system inflammatory lesions (By similarity). Acts as a regulator of Toll-like receptor 4 (TLR4) signaling triggered by lipopolysaccharide (LPS) during systemic inflammation; directly binds LPS (PubMed:25860173). Acts as a mediator of both programmed and necrotic cell death (PubMed:19557008, PubMed:33472215). Plays a key role in the induction of plasma membrane rupture during programmed and necrotic cell death: oligomerizes in response to death stimuli to mediate plasma membrane rupture (cytolysis), leading to release intracellular molecules named damage-associated molecular patterns (DAMPs) that propagate the inflammatory response (PubMed:33472215). Plays a role in nerve regeneration by promoting maturation of Schwann cells (PubMed:31526566). Acts as a regulator of angiogenesis (PubMed:25766274, PubMed:30354207). Promotes the formation of new vessels by mediating the interaction between capillary pericyte cells and endothelial cells (PubMed:25766274, PubMed:30354207). Also mediates vascular functions in penile tissue as well as vascular formation (PubMed:24979788). Promotes osteoclasts development by enhancing the survival of prefusion osteoclasts (PubMed:30700695). Also involved in striated muscle growth and differentiation (PubMed:31091274). Also involved in cell senescence in a p53/TP53 manner, possibly by acting as an indirect regulator of p53/TP53 mRNA translation (PubMed:23690620, PubMed:29073078). Secreted form generated by cleavage, which has chemotactic activity (PubMed:23142597). Acts as an anti-inflammatory mediator by promoting monocyte recruitment, thereby ameliorating atherosclerosis (PubMed:32883094). Homooligomer. By nerve injury (PubMed:9465296). Expression is activated by p53/TP53 (PubMed:23690620). Cleaved by MMP9 protease to generate the Secreted ninjurin-1 form. N-linked glycosylation is required for homooligomerization. No visible phenotype in most cases (PubMed:24347169, PubMed:27815839). Some mice have dome-shaped heads and die within 2 months after birth (PubMed:27815839). Mice show abnormal behavior, reminiscent of obsessive-compulsive disorder: mice exhibit compulsive grooming-induced hair loss and self-made lesions as well as increased anxiety-like behaviors (PubMed:27815839). Mice are prone to systemic chronic inflammation in the skin, liver, kidney and pancreas (PubMed:29073078). During inflammation, reduced motility of bone marrow-derived macrophages and protrusive membrane dynamics are observed (PubMed:24917672). Mice also display attenuated susceptibility to experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis: attenuated susceptibility is caused by reduced leukocyte infiltration and decreased adherence of leukocytes on retinal vessels (PubMed:27815839). Abolished ability to mediate plasma membrane rupture downstream cell death, without affecting GSDMD pore formation (PubMed:33472215). Conditional deletion in pericytes impairs vessel maturation and blood flow recovery in hind limb ischemia (PubMed:30354207). Belongs to the ninjurin family.