Increased engraftment of Notch4-IC–transduced cord cells compared with MIG-transduced cord cells in β₂-microglobulin^–/– NOD/SCID mice. Lineage-depleted cord cells were retrovirally transduced with MIG and Notch4-IC (n = 4) and injected into sublethally irradiated β₂-microglobulin^–/– NOD/SCID mice. Every 3 weeks, bone marrow aspirations were performed, and cells were stained with CD45 and GFP and analyzed by FACS to determine human engraftment. A paired t test was used to determine differences in engraftment. Error bars indicate the standard error of the mean. *P ≤ .05. CD45⁺GFP⁺ cells are indicated by ▪; CD45⁺GFP^– cells, by ▦; total CD45⁺ cells, by ▧.