In CD7+/CD34+-derived leukemia, the proportion of IKZF1del positive cells raised to 100% in virtually all (5+/6 mice, 2 experiments) mice, indicating the reproducible selection of the IKZF1del clone, while it was barely detectable in CD7+/CD34−-derived xenografts (0.01% in 2/4 mice, 2 experiments, Figure 5C). Here, CD7 is linked to leukemia.