NOTCH1 and acute lymphoblastic leukemia: Aberrant activation of NOTCH1 was originally identified in T-ALL cases harboring the t(7;9)(q34;q34.3) chromosomal translocation, through which the intracellular form of NOTCH1 (ICN1) gene fuses to the TCR beta regulatory element, leading to expression of a constitutively active, truncated form of NOTCH1 (45).