NOTCH1 and acute lymphoblastic leukemia: NOTCH1 signalling is identified in the pathogenesis of T-acute lymphoblastic leukaemia/lymphoma (T-ALL) by the activation of NOTCH1 mutations in over 60% of T-ALLs; examples include the heterodimerisation (HD) domain mutation of NOTCH1 found in 20% of T-ALLs, which leads to ligand-independent receptor activation [57].