TKTL1 and B-cell chronic lymphocytic leukemia: Like NTS, the growth factor BDNF, a member of the neurotrophin family, is known to participate in B-cell apoptosis resistance via TrkB, its TKR.21 The concomitant effects of TrkB and NTSR2 on B-CLL lymphocyte survival depended on a physical interaction between these receptors, which was strengthened by BDNF activation (Figure 8, left panel).