NRAS and acute lymphoblastic leukemia: Interestingly, although a common NRAS mutation was identified at every time point during the study (T-ALL at diagnosis, AML upon lineage switch, and T-ALL or AML in SCID mice) suggesting that both T-ALL and AML were derived from a common founding clone, the TCR rearrangement observed in T-ALL at diagnosis was not observed in patient’s AML cells upon switch nor the cells in SCID mice.