CSF2 and acute myeloid leukemia: A new commercial immunodeficient mouse strain that can assist with AML PDX engraftment is the MISTRG (M‐CSFh/h IL‐3/GM‐CSFh/h hSIRPh/h TPOh/h Rag2−/− Il2rg−/−) mouse that has human IL‐3, GM‐CSF, TPO, and M‐CSF genes knocked‐in to replace their murine counterparts, thereby expressing physiologically relevant levels of these cytokines.