Likewise, we also analysed the effects of blocking the Notch signalling pathway since Notch inhibitors seem to enhance B‐cell ALL chemosensitivity [19], and our results showed that in co‐culture CP fibroblasts upregulated the expression of the Notch ligand JAG1 (Jagged‐1) (Figure 4B) and leukaemic cells expressed Notch receptors and increased levels of ADAM10, an essential protease for Notch pathway activation (Figure 4E). This evidence concerns the gene JAG1 and acute lymphoblastic leukemia.