Chemokine that induces chemotaxis of cells expressing CCR5 or CCR1. Inhibits HIV replication in peripheral blood monocytes that express CCR5. Interacts with CCR5. CCL4L1 and CCL4L2 genes differ in their non-coding regions. Thus, alternative splicing events differ between the two genes. Detected in B-cells. The copy number of the CC4L1 gene varies among individuals; most individuals have 1 to 6 copies in the diploid genome. Belongs to the intercrine beta (chemokine CC) family.