RT-PCR analysis of total GATA-2, retroviral GATA-2, and β-2m RNA levels in naive and transduced immature bone marrow cells. RNAs from naive bone marrow cells fractionated by counterflow centrifugal elutriation at a flow rate of 25 mL/minute (FR 25) or 35 mL/minute (FR35) and expressing high levels of c-kit (Kit^HI) but lacking lineage-marker expression (Lin-)14 and from cells expressing the Sca-1 antigen but lacking lineage-marker expression were used as controls for high-level endogenous GATA-2 expression. RNAs from Sca-1⁺Lin⁻ cells expressing the GATA-2irGFP and control irGFP vector, as indicated, were obtained as described in Materials and Methods. RNA from a murine erythroleukemia cell line expressing the GATA-2irGFP vector served as a positive control for the retroviral GATA-2 RNA. Predetermined amounts of each sample RNA that yielded approximately equal β-2m signals (bottom panel) within the linear range of the assay were used to assess the level of total GATA-2 RNA (top panel; endogenous plus retroviral) and retroviral GATA-2 RNA (middle panel).