Cytotoxicity of NVP-LAQ824 against patient MM cells and normal B cells. (A-C) The effect of NVP-LAQ824 on DNA synthesis of freshly isolated primary patient MM cells was examined at 24, 48, and 72 hours. ³H-thymidine uptake of patients' MM cells was inhibited by NVP-LAQ824 (0.01-1 μM). IC₅₀ was observed at 10 to 100 nM by 24 to 48 hours, and less than 10 nM by 72 hours. Almost complete inhibition was seen with 100 nM by 48 hours, and with 10 nM at 72 hours. (D-F) The effects were confirmed using MTS assay. Patient 1 (♦), patient 2 (▪), patient 3 (▴), patient 4 (•), patient 5 (⋄), patient 6 (□), and patient 7 (▵). Thymidine uptake: (A) 24 hours, (B) 48 hours, and (C) 72 hours. MTS assay: (D) 24 hours, (E) 48 hours, and (F) 72 hours. The effect of NVP-LAQ824 was also assessed on normal B cells unstimulated (♦) and stimulated (▪) at 24 hours (G), 48 hours (H), and 72 hours (I). Error bars represent ± 1 SD of a triplicate experiment.