(A–C) HIV-1 DNA kinetics in p21 siRNA–treated CMK cells. Cells were infected by VSV-G–pseudotyped HIV-1 after siRNA treatment. (A) Total levels of HIV-1 cDNA were determined by real-time PCR at 7 hours after infection. (B) At 20 hours after infection, more 2-LTR circles were detected in p21 siRNA–treated cells than in control siRNA–treated cells. (C) At 24 hours after infection, p21 siRNA–treated cells had a significantly increased amount of integrated viral DNA in comparison with control cells. Each sample (500 ng) was tested in triplicate (47–49). Results are representative of 3 separate experiments. (D and E) Detection of HIV-1 2-LTR circle and provirus levels in CD34⁺ primary cells using quantitative PCR. (D) HIV-1 2-LTR circles were detected at 16 hours after infection. (E) HIV-1 integration was increased significantly in p21 siRNA–treated cells in contrast with control siRNA– or mock-treated cells. Each bar represents the mean from 4 individual tests, with each sample run in triplicate. Each sample was tested in an equal amount of total cellular DNA from 6 × 10³ CD34⁺ primary cells.