Rabbit Osteopontin (OPN) (also known as SPP1, Secreted Phosphoprotein 1, bone sialoprotein I, ETA-1, or early T-lymphocyte activation-1) is a multifunctional phosphorylated glycoprotein involved in immune regulation, cell adhesion, and tissue remodeling in rabbits (Oryctolagus cuniculus). Osteopontin interacts with integrins (such as αvβ3, αvβ1, and α4β1) and CD44 receptors, activating signaling pathways that regulate cell migration, inflammatory responses, and extracellular matrix remodeling. In rabbits, OPN is produced by osteoblasts, macrophages, epithelial cells, and activated T lymphocytes, and contributes to bone metabolism, immune responses, and tissue repair. Rabbit osteopontin has been studied extensively in models of cardiovascular disease, particularly atherosclerosis, where it is associated with vascular inflammation, macrophage recruitment, and plaque development. It also plays roles in wound healing, inflammatory responses, and tissue remodeling following injury or infection. While osteopontin supports immune defense and repair processes, excessive or prolonged expression may contribute to chronic inflammation and fibrotic tissue changes. Because rabbits are widely used in cardiovascular, inflammatory, and tissue repair research, characterization of rabbit osteopontin supports studies of immune signaling, vascular inflammation, extracellular matrix remodeling, and disease pathogenesis relevant to both veterinary health and human biomedical research.