NOTCH1 and B-cell chronic lymphocytic leukemia: In conclusion, our data confirmed the presence of NOTCH1 mutations in HSCs of CLL patients and showed for the first time a common nonmutational NOTCH1 activation occurring early in CLL hematopoiesis and represent a rationale for the use of therapies targeting the NOTCH1 signaling in CLL aimed to inhibit the survival of CLL-initiating cells.