CD40LG and B-cell chronic lymphocytic leukemia: Together with our recent finding that bfl-1 mRNA expression levels are decreased in apoptosis-sensitive cells during spontaneous apoptosis in vitro (Morales et al, 2005) and the finding by Kater et al (2004) that CD40L, known to promote survival of B-CLL cells in vivo, induces the expression of bfl-1 in B-CLL cells, protecting them from spontaneous and fludarabine-induced apoptosis in vitro, this finding suggests that bfl-1 may be important for the extended survival of the leukaemic cells in vivo.