31 By disrupting the Bcl-2–IP3R interaction, BIRD-2 abrogates Bcl-2 control over IP3R-mediated Ca2+ elevation and induces Ca2+-mediated apoptosis in primary human CLL cells29 and diffuse large B-cell lymphoma cells.32 Notably, BIRD-2 does not kill normal cells, including human lymphocytes isolated from peripheral blood29 and normal murine embryonic fibroblasts (F Zhong and C Distelhorst, unpublished data). This evidence concerns the gene ITPR1 and B-cell chronic lymphocytic leukemia.