Cynomolgus Monkey (Macaca fascicularis) CXCL4 (C-X-C motif chemokine ligand 4), also known as Platelet Factor 4 (PF4), is a CXC chemokine belonging to the platelet chemokine subgroup of the CXC chemokine family and is primarily released from α-granules of activated platelets. In cynomolgus monkeys, CXCL4 is produced mainly by platelets and megakaryocytes and is rapidly released during platelet activation, vascular injury, or inflammatory responses. CXCL4 plays important roles in hemostasis, inflammation, and immune modulation, influencing the behavior of monocytes, neutrophils, and other leukocytes, and interacting with glycosaminoglycans on endothelial cells and platelets to regulate platelet aggregation, vascular repair, and leukocyte recruitment at sites of tissue damage. Because cynomolgus monkeys share close genetic, physiological, and immunological similarities with humans, CXCL4 in this species is commonly studied in preclinical models of thrombosis, cardiovascular disease, and inflammatory disorders, including investigations of platelet activation and immune–coagulation interactions. As a result, cynomolgus monkey CXCL4 is important in translational biomedical research, particularly in studies evaluating antithrombotic therapies, inflammatory signaling pathways, and platelet-mediated immune responses relevant to human disease.