FIG. 4.

Retroviral transcriptional transactivators fail to inhibit RNAi in human cells. 293T cells were cotransfected with vectors expressing HA-tagged forms of the cellular proteins TRIM5α and β-arrestin. The cells were also cotransfected with pSuper-based expression plasmids that produce shRNAs specific for TRIM-5α (+) or with pSuper as a control (−) and with a vector expressing the indicated wild-type or mutant retroviral transcription factors or with the parental pBC12/CMV as a control (Neg). At 48 h posttransfection, the cells were harvested and lysed and equal amounts of the cellular extracts were used for a Western blot analysis using an HA-specific monoclonal antibody (A). Panel B shows the results of analysis of the same cell extracts but with the amounts of samples loaded normalized to yield equivalent signal intensities, as indicated below the panel.