In a murine mastitis model, administration of LPS into the mammary gland of TLR4(−/−) mice to induce mastitis showed that while knockout mice had significantly lower serum cytokines CXCL1, IL1-ß, IL-6, IL-10, TNF-α, CCL2 and IP10, they also experienced a lower degree of mammary gland involution and maintained increased capacity for milk production as compared to wild-type littermates [15]. Here, CCL2 is linked to mastitis.