NOTCH1 and acute lymphoblastic leukemia: Digging deeper into the molecular mechanism underlying the possible Notch3-UPR cross-talk in T-ALL cells, we focused our in vitro studies on the Notch3-overexpressing TALL-1 leukemic cells, which display constitutive activation of Notch327, while neither bearing Notch1-activating mutations nor displaying Notch1 activation28.