Bovine Regakine-1 (also known as CCL28, mucosae-associated epithelial chemokine, or MEC) is a member of the CC chemokine family, a group of small secreted proteins that regulate leukocyte trafficking and mucosal immune responses. In cattle (Bos taurus), Regakine-1/CCL28 is primarily produced by epithelial cells of mucosal tissues, including the mammary gland, respiratory tract, and gastrointestinal tract, where it contributes to immune cell recruitment and mucosal immunity. This chemokine signals mainly through the CCR10 receptor, and to a lesser extent CCR3, promoting chemotaxis of IgA-secreting plasma cells, T lymphocytes, and other immune cells to mucosal surfaces. In bovine physiology, Regakine-1 plays an important role in mammary gland immune defense, particularly during lactation, where it helps recruit IgA-producing cells to the mammary epithelium, supporting antibody secretion into milk and enhancing protection of the mammary gland and neonate against pathogens. Regakine-1 is also involved in immune responses to mucosal infections and inflammatory conditions, including mastitis, where chemokine-mediated leukocyte recruitment contributes to host defense. Because of its role in mucosal immunity, antibody-secreting cell trafficking, and epithelial immune signaling, bovine Regakine-1 is studied in research on mammary gland immunity, mucosal immune regulation, and host–pathogen interactions relevant to cattle health and dairy production.