Fittingly, BAFF transgenic mice exhibited normal cell distributions and differentiation of precursor/progenitor B-lineage cells.[11], [12], [17] Here, we show that primary leukemia B-cell precursor ALL (B-ALL) express functional receptors of the BAFF-system, particularly BAFF-R, and that their stimulation by BAFF potentiates cell proliferation and results in the engagement of survival pathways. This evidence concerns the gene TNFSF13B and acute lymphoblastic leukemia.