Mouse CCL4 (C-C motif chemokine ligand 4, also known as MIP-1β, macrophage inflammatory protein-1 beta) is a pro-inflammatory chemokine that regulates recruitment and activation of immune cells during inflammatory and infectious responses in mice (Mus musculus). CCL4 primarily signals through the CCR5 receptor, promoting chemotaxis of monocytes, macrophages, dendritic cells, natural killer (NK) cells, and activated T lymphocytes to sites of infection, inflammation, or tissue injury. In mice, CCL4 is produced by activated macrophages, dendritic cells, T lymphocytes, epithelial cells, and endothelial cells in response to inflammatory stimuli such as microbial products and cytokines including TNF-α and IL-1β. Mouse CCL4 is widely studied in experimental models of viral and bacterial infections, autoimmune diseases, cancer, and inflammatory disorders, where chemokine-driven immune cell recruitment contributes to pathogen clearance and immune regulation. It plays important roles in murine models of HIV-related research (through CCR5 signaling), experimental autoimmune encephalomyelitis (a model of multiple sclerosis), inflammatory arthritis, and tumor immunology, where leukocyte infiltration influences disease progression. Because mice are the most widely used genetic model organism for studying immune function, characterization of mouse CCL4 has been essential for understanding CCR5-mediated leukocyte trafficking, inflammatory signaling pathways, and host–pathogen interactions, providing insights relevant to human immunology and therapeutic development.