MYC and acute lymphoblastic leukemia: SLC7A5 has a key role in peripheral T cells, controlling mTORC1 activity and c-Myc expression,21 known drivers of T-ALL.13, 43 In contrast deletion of Slc7a5 in T-cell progenitors in the thymus does not impair normal T-cell development.21 However, SLC7A5 loss dramatically impairs the development of T-cell malignancy: Ptenfl/flSlc7a5fl/flLck-Cre+ mice thus showed prolonged survival (358 days median surivival) compared with the rapid morbidity of Ptenfl/flLck-Cre+ mice (68 day median survival) (Figure 4c).