The role of signaling events in the regulation of GCP-2–induced CXCR2 internalization.

(A) Inhibition of GCP-2–induced chemotaxis of CXCR2-expressing HEK 293 cells by wortmannin. The cells were treated with 10, 100, or 1000 nmol/L wortmannin for 1 hour at 37°C, and washed and subjected to a chemotaxis assay in response to 100 ng/mL GCP-2, as described in “Materials and methods.” A representative experiment of 4 performed is shown. *P < .05, **P < .01 for the response after the treatment, vs without treatment, by wortmannin. (B) Enhancement of GCP-2–induced internalization of CXCR2-transfected HEK 293 cells by wortmannin. CXCR2-transfected cells were incubated with 360 ng/mL GCP-2 for 2 hours at 37°C. Prior to (for 1 hour) and during the exposure to GCP-2, the cells were treated with 10, 100, or 1000 nmol/L wortmannin, washed, stained with anti-CXCR2-specific antibodies, and subjected to fluorescence-activated cell sorting (FACS) analysis, as described in “Materials and methods.” Each value represents the mean ± SD of 4 to 6 independent experiments. ***P < .001 for the response in the presence, vs the response in the absence of wortmannin.