Proteolytic products generated by mMCP-11 induce leukocyte migration via 1 or more G protein–coupled receptors. (A) The effect of nafamostat on mMCP-11–elicited leukocyte migration was examined in the transwell migration assay. mMCP-11 was added to the lower chamber together with nafamostat (experiment 2 [Exp2]) or control vehicle dimethyl sulfoxide alone (experiment 1 [Exp1]), and then the upper chamber containing leukocytes was placed onto the lower chamber to start the migration assay. In experiment 3 (Exp3), nafamostat was added to the lower chamber after the culture medium in the lower chamber had been incubated with mMCP-11 at 37°C for 2 hours prior to the transwell migration assay. The number of cells recovered from the lower chamber at the end of the migration assay is shown (mean ± SD, n = 3 chambers each). (B) The transwell migration assay of BMBAs was performed by using a culture medium that was either serum sufficient (including 10% fetal calf serum) or serum deficient (including 0.1% BSA) in both upper and lower chambers. The number of cells that had migrated into the lower chamber after 2-hour incubation at 37°C is shown (mean ± SD, n = 3 chambers each). (C) As in experiment 3, nafamostat was added to the lower chamber after the culture medium had been incubated with mMCP-11 for 2 hours prior to the transwell migration assay, while the indicated types of cells were pretreated with PTX or control PBS for 1 hour and transferred to the upper chamber. The number of cells recovered from the lower chamber at the end of the migration assay is shown (mean ± SD, n = 3 chambers each). Data shown in panels AC are representative of at least 3 independent experiments. **P < .01; ***P < .001.