Expression of BAFF-R, BCMA, and TACI on WM cells. Tumor cells from the WM cell line (WSU-WM) and WM patients were stained with biotin-conjugated BLyS, anti-BAFF-R, anti-BCMA, or anti-TACI for 30 minutes at 4°C, then washed and incubated for 30 minutes with PE-streptavidin. Isotype and fluorochrome controls were done in parallel with each sample (white histograms). Gray histograms correspond to CD19⁺CD138⁺ cells from a representative example of each subtype. Results shown are from 5 representative WM samples, out of a total of 12 patient samples analyzed.