To determine whether cell-cycle restriction protects pre-LSCs against chemotherapeutic agents typically used for human T-ALL, we looked for enrichment of GFPhi DN3 cells following treatment of H2B-GFP;Lmo2Tg mice with a combination of vincristine, dexamethasone and l-asparaginase (VXL)27. Here, H2BC21 is linked to acute lymphoblastic leukemia.