NOTCH1 and acute lymphoblastic leukemia: Remarkably, the effects of miR-181a-1/b-1 change depending on the expression level of Notch1. If the expression of Notch1 is high, the deletion of the miR-181a-1/b-1 gene strongly delays T-ALL development, whereas the deletion leads to a full inhibition of T-ALL if Notch1 expression is lower.