Growth factors and coculture with BM microenvironment cells do not protect WM cells against the combined perifosine and bortezomib-induced cytotoxicity. (A) BCWM.1 cells were cultured with the combination perifosine (5 μM and 10 μM) and bortezomib (10 nM) for 48 hours, in the presence or absence of BMSCs. Cell proliferation was assessed using the [³H]-thymidine uptake assay. (B) BCWM.1 cells were cultured with either perifosine (10 μM), bortezomib (5 nM and 10 nM), or the combination in presence of IL-6 (50 ng/mL) or CD40L (3 μg/mL) for 48 hours. Cytotoxicity was assessed by the MTT assay. (C) PBMCs from 3 healthy donors with either perifosine (10 μM), bortezomib (5 nM and 10 nM), and the combination for 48 hours. Cytotoxicity was assessed by MTT assay. (D) Colony-forming cell assay. Nonadherent mononuclear cells were cultured using methylcellulose semisolid technique cultured with either single agents or the combination. The plates were read at days 14 to 16. BFU-E indicates burst-forming units–erythroid; CFU-GM, colony-forming units–granulocyte/macrophage; CFU-M, colony-forming units–macrophage; CFU-GEMM, colony-forming units–granulocyte/erythroid/macrophage/megakaryocyte. Data represent mean plus or minus SD of triplicate experiments.