BLyS promotes survival of WM cells. CD19⁺CD138⁺ cells (0.25 × 10⁶ cells/well) from WM patients (n = 4) were cultured in 48-well plates in RPMI 10% FBS in the presence or absence of 100 ng/mL BLyS. One week following treatment, the cells were harvested and assayed for viability using annexin-V/PI staining. Cell viability in the presence of BLyS was normalized to the media-alone control and is presented as relative viability.