RAG1 and acute myeloid leukemia: To assess the effect of IMPDH inhibition on human AML cells in vivo, we transplanted the MPA‐sensitive PDX cells with MLL‐fusions (Appendix Table S1) to the immunodeficient NOD/RAG1/2−/‐IL2Rγ−/− (NRGS) mice expressing human SCF, IL‐3, and GM‐CSF (Barve et al, 2018), and treated them with IMPDH inhibitors (MMF or FF‐10501‐01) for 3 weeks (Fig 2H).