At the time of killing, mice in the IL4 group were almost devoid of leukemia cells in the bone marrow (mean 1.8% in the IL4 group versus 97% in the control group, P<0.0001; Figure 5c) and spleen (mean 3.8% in the IL4 group versus 76% in the control group, P<0.0001; Supplementary Figure 9e), and had elevated levels of IL4 in the bone marrow (Supplementary Figure 9f), demonstrating that IL4 had strong antileukemic effects on AML cells in an in vivo context. Here, IL4 is linked to leukemia.