Perifosine induces decrease in proliferation and cytotoxicity. (A) Thymidine uptake assay. MM.1S and BCWM.1 cells were cultured with perifosine (2 to 30 μM) for 48 hours. BCWM.1 (■), MM.1S (♦). (B) BCWM.1 cells were cultured with perifosine (2 to 50 μM) for 24 hours (♦) and 48 hours (■). (C) Several IgM-secreting cell lines, RL (♦), MEC-1 (■), WM-WSU (Δ) were cultured with perifosine (2 to 50 μM). (D,E) Freshly isolated BM CD19 + tumor cells from 3 patients with WM (D) and PBMCs from 3 healthy donors (E) were cultured with perifosine (5 to 50 μM). Cytotoxicity was assessed by the MTT assay (C-E). All results represent mean (± SD) of triplicate experiments. (F) Colony forming-cell assay. Nonadherent mononuclear cells were cultured using methylcellulose semisolid technique in absence and presence of perifosine (5 μM and 10 μM) for 14 days. Burst forming units-erythroid (BFU-E), colony-forming units-granulocyte/macrophage (CFU-GM), colony-forming units-macrophage (CFU-M), and colony-forming units-granulocyte/erythroid/macrophage/megakaryocyte (CFU-GEMM).