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 Mouse MCP-3 is an 8.5 kDa protein containing 74 amino acid residues including the four highly conserved cysteine residues present in the CC chemokines.