Cynomolgus Monkey (Macaca fascicularis) CCL2 (C-C motif chemokine ligand 2, also known as monocyte chemoattractant protein-1, MCP-1) is a pro-inflammatory chemokine that plays a central role in recruitment and activation of monocytes, macrophages, dendritic cells, and memory T cells during immune responses. CCL2 primarily signals through the CCR2 receptor, activating intracellular pathways that promote leukocyte migration, cytokine production, and coordination of innate and adaptive immunity at sites of infection, inflammation, or tissue injury. Highly homologous to human CCL2, cynomolgus CCL2 is widely studied in nonhuman primate models of infectious and inflammatory diseases, including tuberculosis, dengue, influenza, and SARS-CoV-2, where it contributes to monocyte and macrophage recruitment to infected tissues and influences inflammatory disease progression. CCL2 also plays roles in atherosclerosis, autoimmune disease models, and cancer research, where monocyte-derived macrophages contribute to tissue remodeling and immune-mediated pathology. Because cynomolgus monkeys are extensively used in preclinical drug development and immunology research, characterization of CCL2 is important for evaluating chemokine-mediated immune cell trafficking, inflammatory responses, and the effects of anti-inflammatory or immunomodulatory therapeutics. As a biomarker of monocyte recruitment and inflammatory activation, cynomolgus CCL2 provides valuable translational insight into chemokine signaling pathways relevant to human disease.