Correction of anemia at lower level of modified WBCs when tEpoR is coexpressed with the therapeutic globin gene. (□) Mice transplanted with LG/HA-Y1 transduced marrow cells. (■) Mice transplanted with LG transduced marrow cells. (A) Correlation of modified RBC (RBC⁺), hematocrit values (Hc), total hemoglobin concentrations (Hb), and reticulocyte percentages (Retic) with modified WBC (WBC⁺) of transplanted β-thalassemic mice. The hatched line separates data with WBC⁺ below and above 20%. (B) Mean ± SD and individual modified RBC percentages, hematocrit values, total hemoglobin concentrations, and reticulocyte percentages of mice with WBC⁺ below and above 20%. Numbers below the graphs precisely indicate the mean percentage of modified WBCs.