NOTCH1 and acute lymphoblastic leukemia: RNA expression studies also revealed a shared signature in fish, mouse, and human T-ALL, suggesting conservation of key molecular circuitry for a ‘Notch profile.’ They hypothesized that NOTCH1 mutations are likely an initiating event in human T-ALL that expands pre-malignant thymocytes, with only a subset of cells acquiring additional mutations to become fully transformed.