Detection of endogenous human BAFF-R with 044580. BJAB and Jurkat cells were stained with A) 20ug/ml (and 2-fold dilutions) and B) 2ug/ml of 044580 in 50ul FACS buffer (PBS, 5% fetal calf serum, 0.02% azide), revealed with anti-mouse-PE (1:200) and then analyzed by flow cytometry.