Total BM CD34⁺ cells were cultured with 200 ng/mL SCF and 100 ng/mL each of IL-3 and IL-6, and on d1, d5, d6, d8, or d9 they were infected over fibronectin with G1Na or LNL6 supernatant. On d5 and d8, cultured CD34⁺ cells were first separated into CNR and CR cells based on residual PKH2 fluorescence and then transduced with either retroviral vector. On d6 and d9, cultured CD34⁺cells were first transduced and then fractionated into CNR and CR cells.

Number of colonies is reported as the number of G418-resistant colonies per total number of assayable progenitors corrected for a total of 10³ cells analyzed.

Mock-infected cultures of CD34⁺ cells did not contain any G418-resistant colonies at any time point. The number of total assayable progenitors produced in mock-infected cultures of CD34⁺ cells was similar to that observed in cultures of transduced cells.

Transduction efficiency calculated as (no. of G418-resistant colonies/no. of cells plated in G418) × (no. of cells plated without G418 × 100/no. of unselected colonies).