NTSR2 and B-cell chronic lymphocytic leukemia: An additional pro-survival pathway has been recently described whereby NLCs secrete brain-derived neurotrophic factor (BDNF), leading to the activation of the neurotensin receptor 2/tropomyosin-related kinase receptor B (NTSR2/TrkB) complex on CLL cells and the subsequent induction of anti-apoptotic proteins [78,79].