eIF-2α is phosphorylated in multiple myeloma cells treated with a variety of cytotoxic agents. The indicated multiple myeloma cell lines were cultured in 50 μM tunicamycin (TM), 1 μM brefeldin A (BfA), 30 μM melphalan (Mel), 250 nM staurosporine (STS), or the indicated concentration of the proteasome inhibitors epoxomycin (EPOX), PSI, or bortezomib (BZ). After 12 and 24 hours of treatment, cell viability was determined by Annexin V–FITC and propidium iodide staining, and whole cell lysates were isolated to sequentially evaluate the amount of phosphorylated and total eIF-2α present by Western blot analysis. The data are representative of at least 3 different experiments.