Tunicamycin induces cytotoxicity and decrease in proliferation. (A) Thymidine uptake assay. BCWM.1 WM cells were cultured with tunicamycin (0.01 μg/mL to 5 μg/mL) for 48 hours. (B) BCWM.1 cells were cultured with tunicamycin (0.01 μg/mL to 5 μg/mL) for 24 hours (△) and 48 hours (■), then cytotoxicity was studied. (C) Freshly isolated BM CD19⁺ cells from 3 patients with WM were cultured with tunicamycin (0.01 μg/mL to 1 μg/mL) for 48 hours. (D) Absence of cytotoxicity was observed on freshly isolated peripheral blood CD19⁺ from 3 healthy donors cultured with tunicamycin (0.01 μg/mL to 5 μg/mL) for 48 hours. Cytotoxicity was assessed by the MTT assay (B-D). (E) Salubrinal (50 μM and 75 μM) do not protect BCWM.1 cells from tunicamycin-induced (0.1 μg/mL and 1 μg/mL) cytotoxicity at 48 hours. (F) ELISA of BCWM.1 supernatant. IgM secretion was decreased after 12 hours and 24 hours of treatment with tunicamycin (0.05 μg/mL and 0.1 μg/mL).