GFI1 and T-cell leukemia: We also employed two cultured human cell models: (i) SupT1 T-cell lymphoblasts ectopically overexpressing GFI1 to determine the effects of increased GFI1 expression (Supplementary Fig. 1b) and (ii) a Jurkat T-cell leukemia line in which GFI1 was knocked-out using a Crispr/Cas9 strategy (Supplementary Fig. 1c).