CCL2 and neoplasm: In another melanoma study with B16-F10 and M3 tumor models, the TLR7 agonist, imiquimod, was observed to significantly increase mast cell production of the chemokine CCL2 in a TLR7-dependent fashion, which subsequently leads to the recruitment of effector plasmacytoid dendritic cells that ultimately mediate cell killing and tumor control [93].