Conditional RNAi Leukemia Modeling

All mouse experiments were approved by the Cold Spring Harbor animal care and use committee. For conditional RNAi experiments in vivo, Tet-on MLL-AF9/Nras^G12D leukaemia cells were transduced with TRMPV-Neo-shRNA constructs, followed by transplantation into sub-lethally irradiated recipient mice, as described previously¹⁰ . For shRNA induction, animals were treated with doxycycline in both drinking water (2 mg ml⁻¹ with 2% sucrose; Sigma-Aldrich) and food (625 mg kg⁻¹, Harlan laboratories). For JQ1 treatment trials, a stock of 100 mg ml⁻¹ JQ1 in DMSO was diluted 20-fold by dropwise addition of a 10% 2-hydroxypropyl-β-cyclodextrin carrier (Sigma) under vortexing, yielding a 5 mg ml⁻¹ final solution. Mice were intraperitoneally injected daily with freshly diluted JQ1 (50 or 100 mg kg⁻¹) or a similar volume of carrier containing 5% DMSO.