Retroviral transduction of CD34⁺CD38⁻CD10⁻ FL cells does not affect their capacity to develop along the B-cell lineage. The CD34⁺CD38⁻CD10⁻ FL population was isolated (A), transduced with virus harboring the IRES-GFP sequence, and cultured for 18 days on a stromal cell monolayer (B). Cell suspensions were stained with the indicated Tricolor- and PE-labeled antibodies and analyzed on a FACScan. Isotype-matched control antibodies were used in all experiments.