RNAi effectors and APOBEC 3G-mediated HIV-1 repression involve different pathways. HeLa CD4+ cells were transfected with the indicated siRNA. 48 hours later cells were analyzed for RCK/p54 and LSm-1 expression (right panel) or co-transfected with 1 μg of pNL4-3Δvif (lacking vif gene) and pcDNA or expression vectors for wild-type APOBEC3G or APOBEC3G double mutant lacking both deaminase and antiviral activity, A3G H65R/H257R . HIV-1 production was measured 24 hours post-transfection in culture supernatant by quantifying p24 antigen (top left panel). Numbers on the top of the columns are fold increase relative to the respective Scr. Numbers on the top of Scr samples in A3Gwt and A3Gdm represent fold increase relative to Scr in pCDNA transfected cells. Infectivity assay was performed using equal amounts of p24 antigen to infect HeLa CD4+ cells. HIV-1 p24 antigen was measured 48 hours post infection (lower left panel). A representative experiment out of five is shown.