Role of Rab GTPases in CXCR2 internalization in HEK293 cells.

Cells stably expressing CXCR2 were transiently transfected with plasmids for EGFP-Rab5 or EGFP-Rab5-S34N (A), plasmids for EGFP-Rab11a or EGFP-Rab11a-S25N (B), or plasmids for EGFP-Rab7 or EGFP-Rab5-T22N (C). Cells were incubated with 75 nCi/mL (2.775 KBq/mL)¹²⁵I-CXCL8 at 4°C for 1 hour. Unbound¹²⁵I-CXCL8 was removed by washing at 4°C. Cells were warmed to 37°C for the indicated time period. ¹²⁵I-CXCL8 remaining at the cell surface was removed with acetic acid (0.2 M, pH. 2.5) containing 0.5 M NaCl, and the internalized¹²⁵I-CXCL8 was quantified on a γ-counter. Values represent the means ± SEMs of 3 independent experiments performed in duplicate. Data were analyzed using Student paired t test (*P < .05).