Similarly, our results showing the upregulated expression of JAG1 (Jagged‐1) and ADAM‐10 in CP fibroblasts and BCP‐ALL cells, respectively, and the increased chemosensitivity of leukaemic cells after treatment with a γ‐secretase inhibitor, indicate that the activation of the Notch pathway occurring after CP fibroblast–leukaemia cell interaction is also partially responsible for the resistance to chemotherapy acquired by BCP‐ALL cells. The gene discussed is JAG1; the disease is acute lymphoblastic leukemia.