As shown in Fig 4B and as previously reported, 4-OHT treatment induced efficient CnB1 gene deletion and resulted in a strong arrest in T-ALL expansion (Fig 4C), with the few cells found under these co-culture conditions resulting from the survival of a minor population of cells that escaped full CnB1 gene deletion, detectable by PCR (Fig 4D, MIG lanes). This evidence concerns the gene PPP3R1 and acute lymphoblastic leukemia.