Effect of clathrin on CXCR4 and CCR5 internalization. (A) Jurkat cells were incubated with SDF-1 (500 ng/mL) or SDF-1 plus 0.6 M sucrose in RPMI for 1 hour at 4°C or 37°C. Then CXCR4 expression was examined by immunofluorescence staining. (B) PBMCs were incubated with RANTES (500 ng/mL) in the presence of sucrose, fucoidan, or sulfatide for 1 hour at 37°C. Then CCR5 expression was examined by immunofluorescence staining and flow cytometry.