The MCP proteins are members of the CC chemokine family that signal through CCR2 and, with the exception of MCP-1, other CCR receptors. The MCP proteins chemoattract and activate monocytes, activated Tcells, basophils, NK cells, and immature dendritic cells. The MCP family cross-reacts across species. Recombinant Human MCP-4 is an 8.6 kDa protein containing 75 amino acid residues including the four highly conserved cysteine residues present in the CC chemokines.