LTA-induced chemokine receptor down-modulation is sensitive to PMA, inhibition of Rac1 and PLC, but not to inhibition of TIRAP or PKC. Receptor down-modulation was assessed by flow cytometry after 1 hour of exposure to 100nM chemokine (CCL2 for CCR2; CCL5 for CCR1 and CCR5) or 10 μg/mL LTA, without (■) or with (□) inhibitor (A-B,D) or as specified (C). Conditions are as follow: (A) 20μM TIRAP inhibitor peptide; (B) 100μM Rac1 inhibitor NSC23766; (C) 5μM PKC inhibitor GF109203X and 100nM PMA; (D) 10μM PLC inhibitor U73122. The results are expressed as the percentage of down-modulation and represent the average values from ≥ 4 independent experiments. *P < .05 and **P < .01.