To evaluate the impact of BAFF stimulation on B-ALL functions, primary B-ALL (n = 10) were cultured for 72 h in control medium or in the presence of BAFF-myc and/or CD40L, as we and others have reported that CD40 ligation is mitogenic for B-ALL cells.[39], [40] BAFF alone did not promote substantial cell proliferation (Figure 6A; mean 1.34, range 1.0–1.59-fold increase) whereas, as expected, CD40L was mitogenic for B-ALL cells in most cases (Figure 6A; mean 3.26, range 1.19–5.54-fold increase). The gene discussed is CD40; the disease is precursor B-cell acute lymphoblastic leukemia.