OBJECTIVES: I. Determine the maximum tolerated dose and dose-limiting toxicity of PS-341 in patients with hematologic malignancies. II. Determine the pharmacodynamics of this drug in these patients. III. Determine response to this drug in these patients. IV. Determine the correlation between response of malignancies and proteasome inhibition and apoptosis in peripheral blood mononuclear cells (PBMC) of these patients. V. Determine the correlation between therapy toxicity and proteasome inhibition and apoptosis in PBMC of these patients. VI. Determine the effect of this drug on other molecular markers (i.e., BCL-2 in follicular lymphoma patients and t9;22/BCR/ABL in chronic lymphocytic leukemia patients). VII. Determine the correlation between interleukin-6 serum levels in multiple myeloma patients and drug dosing, toxicity of therapy, extent of protease inhibition, response to therapy, and apoptosis in PBMC of these patients.