VTCN1 and leukemia: To further elucidate the potential mechanisms leading to the enhanced proliferation of LICs, Wright–Giemsa staining was conducted and revealed that there was a much higher number of immature B7-H4-null blast cells in the bone marrow (BM) compared to that of the WT counterparts (36.7±3.4 vs 18.5±1.6%, Supplementary Figure 3a), consistent with the increased infiltration of B7-H4-null leukemia cells in the spleen and liver as indicated by the changes of relative weights and hematoxylin/eosin staining (Supplementary Figures 3b and c).