FIG. 2.

Nef reduces cell surface levels of CXCR4 in several mammalian cell lines. Human and hamster cell lines, which either constitutively coexpress human CXCR4 and CD4 or were transiently transfected with either CXCR4 or CD4 expression plasmids (hCXCR4 or hCD4 transf.), were transfected with expression constructs encoding for Nef.GFP or GFP alone. HeLa Z24 cells were transduced with adenoviral vectors expressing Nef.GFP or GFP. At 2 days posttransfection or posttransduction, relative cell surface levels of CXCR4 and CD4 were assessed by flow cytometry and quantified as described in the legend to Fig. 1. Values obtained for cells expressing GFP alone were set to 100%. Values are the arithmetic means of triplicates + standard deviations and are representative results from two to eight independent experiments.