BLyS promotes survival and proliferation of MM cells. (A) MM cells were cultured in RPMI plus 0.5% BSA alone (□) or with the addition of 0.1 μg/mL BLyS (▤) or 1 ng/mL IL-6 (▪), and cell viability was determined after 7 days. A minimum of 500 cells was counted for each condition. (B-D) MM cells were cultured in 96-well flatbottom microtiter plates in the presence of 1 ng/mL IL-6, 10 ng/mL IGF-I, 0.1 μg/mL BLyS, alone or in combination for 7 days at 37°C in the presence of 5% CO₂. Values represent the mean of triplicate values of a representative experiment (n = 5).