Number of cells per G418R erythroid colony after transduction of CD34⁺ cells with LNL6 or LNC(SCL). Each point represents an individual patient sample. The mean colony size for each patient sample was determined by pooling 30 to 50 colonies in 150 μL PBS, the number of cells was counted, and the result was divided by the number of colonies pooled. Cell counts were performed after culture in agar for 7 (n = 11 experiments), 10 (n = 15 experiments), and 14 days (n = 13 experiments). Statistics were performed using the paired t-test.