Enables chemokine activity. Involved in several processes, including mature natural killer cell chemotaxis; positive regulation of leukocyte migration; and positive regulation of production of molecular mediator of immune response. Acts upstream of or within chemotaxis and release of sequestered calcium ion into cytosol. Located in extracellular space. Orthologous to several human genes including XCL1 (X-C motif chemokine ligand 1). [provided by Alliance of Genome Resources, Apr 2022]