Figure 4. Cell-surface CXCR2 undergoes recycling with ligand stimuli but not nonligand stimuli. Mouse peripheral blood neutrophils were stimulated with KC or formyl peptide and LPS for 30 min at 37°C. Stimuli were removed by extensive cell washing, and the cells were then cultured in the presence of cycloheximide (35 μM) and 10 μM BB94 for 180 min at 37°C for CXCR2 re-expression from the recycling compartment (recycle), as described in Materials and Methods. (Left histograms) Representative data; (right bar graph) cumulative data. Relative cell-staining levels of CXCR2 antibodies were determined by flow cytometry. For the histograms, the x-axis = Log 10 fluorescence, and the y-axis = cell number. The bar graph shows mean ± sd of 4 mice/treatment. Statistical significance is indicated as ***P < 0.001.