Smad7-transduced SRCs give rise to more clonogenic progenitors than do vector-transduced SRCs. (A) Sorting gates used to select human CD34⁺GFP⁺ or CD34⁺GFP^– cells from the BM of NOD/SCID mice. Cells of the appropriate phenotype were sorted, and 5000 cells of each population were placed into CFU assay for detection of CFUs arising from SRCs (CFU-SRC). (B) Representative granulocytic CFU-SRCs (corrected to line 1, dashed line) transduced with vector (left) or Smad7 (right) retrovirus, visualized by light (inset) and fluorescent microscopy, scored between days 10 and 14. (C) Frequency of Smad7 CFU-SRCs relative to corresponding frequency of vector CFU-SRCs, from equal cell inputs. Shown below the graph is mean CFU-SRCs ± SEM of 5 independent pairings, per 5000 input cells, from the 4 independent CB samples showing an increased Smad7 CFU-SRC frequency compared with vector. Inset shows percentage of CFU-SRCs from GFP⁺ and GFP^– Smad7 treatments compared with corresponding vector control. (D) Distribution of multiple hematopoietic lineages (erythroid burst-forming units [CFU-E], granulocyte CFUs [CFU-G], macrophage CFUs [CFU-M], granulocytemacrophage CFUs [CFU-GM], and granulocyte-erythrocyte-macrophage-megakaryocyte CFUs [CFU-GEMM]) within the total GFP⁺ CFU-SRCs, or GFP^– CFU-SRCs (inset). □ indicates vector GFP⁺; ▪, Smad7 GFP⁺. Bars represent the percentage of total CFU-SRCs ± SEM, from 5 independent CB pairings.