LV transduction of human lymphocytes does not require cell proliferation and correlates with cell cycle progression from G₀ to G_1b (A) PBLs labeled with CFSE were cultured in vitro as described in Figure 1. Cells were analyzed 96 hours later for CFSE intensity by flow cytometry. (B) DNA and RNA contents were measured by 7AAD and pyronin Y (PY) staining, respectively. Analysis was performed after 96 hours of culture. The percentage of cells in S/G₂/M is indicated. The R1 gate, encompassing the G₀/G₁ population, was used for further analysis. (C) Histogram of RNA staining of R1-gated cells plotted for PY staining to distinguish G₀ from G₁ cells. The percentage of cells in G₀ or in G₁ is indicated. Data are representative of 3 experiments.