Molecular analysis confirmed that no Notch1DECRREE-derived T-ALL cases harbored 5′ Notch1 genomic deletions (Fig. 2C), demonstrating that the RSS at positions −8131 and +3573 are indeed the main mediators of the ectopic RAG recombination events in the murine Notch1 gene. Here, NOTCH1 is linked to acute lymphoblastic leukemia.