Enzastaurin induced a decrease in proliferation and triggers cytotoxicity. (A) Thymidine uptake assay. BCWM.1 was cultured with enzastaurin (2.5 to 20 μM) or solvent control (DMSO) for 48 hours (●) and 72 hours (▩). (B) Thymidine uptake assay. Several IgM-secreting cell lines, RL, MEC-1, and WM-WSU, were cultured with enzastaurin (2.5 to 20 μM) solvent control (DMSO). (C) BCWM.1 cells were cultured with enzastaurin (2.5 to 20 μM) solvent control (DMSO) for 48 hours. Cytotoxicity was assessed by MTT assay. (D) Several IgM-secreting cell lines, RL, MEC-1, and WM-WSU, were cultured with enzastaurin (2.5 to 20 μM) solvent control (DMSO) for 48 hours. Cytotoxicity was assessed by MTT assay. (E-F) Freshly isolated bone marrow CD19+ tumor cells from 3 patients with WM (E) and PBMCs from 3 healthy donors (F) were cultured with enzastaurin (5 to 20 μM). Cytotoxicity was assessed by MTT assay. (G) Colony-forming cell assay. Negative fraction after CD19+ selection of bone marrow mononuclear cells was cultured using methylcellulose semisolid technique in absence and presence of enzastaurin (15 and 20 μM), and BFU-E, CFU-GM, CFU-M, and CFU-GEMM were counted at day 14. All results represent means (± SD). All experiments have been done in triplicate.