To test the role of Slfn2 in T-cell malignancies, we analyzed whether Slfn2 impaired-function in elektra mice can inhibit the development of T-ALL in an established animal model for T-ALL involving the expression of oncogenic NOTCH1 (intracellular NOTCH1 fragment, ICN1). The gene discussed is NOTCH1; the disease is acute lymphoblastic leukemia.