Fig. 5

siRNA knockdown of cullin 1 hinders surface downmodulation of CD4, but not BST-2, by Vpu. a HeLa-CD4 cells were transfected twice with pooled control or cullin 1 siRNAs. 4 h post the second transfection, the cells were infected with VSV-G pseudotyped DHIV-GFP (Nef−/Vpu−) or DHIV-GFP WARO (Nef−/Vpu+). Cells were subsequently stained to detect surface levels of CD4 and BST-2 between GFP negative (blue line) and GFP positive (red line) populations 48 h post infection. Gray shaded histogram represents an IgG matched isotype control. b A portion of cells from a were lysed and subjected to Western blot to determine the knockdown efficiency of cullin 1. c Quantification of cullin 1 normalized to β-actin from b.