Second, to further establish the weight of leukemic ST2+ Treg cells in the overall role of ST2 in the BM niche, we used a non-irradiated leukemic model and injected MLL-AF9 leukemia cells into WT or ST2−/− mice and additionally depleted Treg cells with anti-CD25 antibody. The gene discussed is KMT2A; the disease is leukemia.