Human Chemokine (C-C Motif) Ligand 23 (CCL23) is a small cytokine belonging to the CC chemokine family. CCL23 is also known as myeloid progenitor inhibitory factor MPIF-1, CK8 and SCYA23. CCL23 cDNA encodes a 120 amino acid residue precursor protein with a putative 21 amino acid residue signal peptide that is cleaved to generate a 99 amino acid residue mature CCL23 (amino acids 22 -120). Additional N-terminal Processing of the 99 amino acid residue variant can generate a 75 amino acid residue peptide (amino acid 46-120) that is significantly more active than the 99 amino acid residue variant. CCL23 binds to CCR1 with high affinity and has chemotactic activity for monocytes, dendritic cells, and osteoclast precursors. CCL23 enhances angiogenesis of endothelial cells, but reduces the proliferation of progenitor cells giving rise to granulocyte and monocyte lineages.