Laboratory animals and mouse bone marrow transplantation assays

All mice were monitored daily and housed in individually ventilated cages cages in specific pathogen free (SPF) or semi-SPF conditions in the KU Leuven animal facility. Mouse experiments were approved and supervised by the KU Leuven ethical committee (ECD P013/2018).

Bone marrow transplantation was performed with hematopoietic stem/progenitor cells harvested from male rosa26 CD2cre C57BL/6 mice. These cells were transduced with retroviral vectors for expression of the genes of interest, with MSCV-based vectors giving constitutive expression or inducible expression based on inversion of a floxed region in the viral vector as described previously.¹⁹ Cells were injected via tail vein injection into sublethal irradiated (5Gy) female recipients C57BL/6 mice. Leukemia development was followed by blood collection from the facial vein every 2 weeks. Secondary and tertiary transplants were performed through injection of malignant cells via tail vein into irradiated (2.5 Gy) female recipients C57BL/6 mice recipient mice. Mice were sacrificed when white blood cell count was over 25,000/µL, when they lost 10% of initial weight or other signs of severe morbidity.