IL2RA and leukemia: To discover additional TFs that may shape the pre-leukemic chromatin landscape in this population, we inferred TF activity from gene expression data using TF activity scoring based on Scenic analysis [27] (Supplementary Fig. 6D) comparing the identified pre-leukemic c-KIT+ CD25+ cell population in the Pax5± mouse from Fig. 6A to murine WT B-cell precursors (Fig. 6D), and as an independent confirmation used the chromatin accessibility profiles, which were acquired in the two additional independent pre-leukemic samples (pre-leukemia 5 and 7).