NOTCH1 mutations often occur in T-cell acute lymphoblastic leukemia/lymphoma (T-ALL) (40) and multiple studies have demonstrated the importance of NOTCH1 signaling for the induction of lymphomagenesis (41–43). A recent study by Kimura et al. suggested that activating NOTCH1 mutations play a role in the genetic evolution of pediatric T-ALL (44). This evidence concerns the gene NOTCH1 and T-cell acute lymphoblastic leukemia.