Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed B-cell non-Hodgkin's lymphoma (NHL) including the following
subtypes:

- B-cell small lymphocytic lymphoma

- Marginal zone lymphoma (extranodal, nodal, or splenic)

- Grade 1-3 follicular lymphoma

- Mantle cell lymphoma

- Waldenstrom's macroglobulinemia

- Bidimensionally measurable disease by CT scan with ≥ 1 lesion measuring > 1.5 cm in a
single dimension

- Relapsed or refractory disease after prior antineoplastic therapy, meeting 1 of the
following criteria:

- No response to prior treatment

- Relapsed disease after prior therapy

- Confirmed CD20-positive disease by immunohistochemistry on biopsy specimen

- Prior transformation allowed provided there is no evidence of aggressive
histology on recent biopsy

- No chronic lymphocytic lymphoma with absolute lymphocyte count > 5,000/mm³

- No CNS involvement

PATIENT CHARACTERISTICS:

- ECOG performance status 0-2

- Absolute neutrophil count ≥ 1,500/mm^3 (≥ 1,000/mm³ if due to extensive bone marrow
involvement with NHL or splenomegaly)

- Absolute lymphocyte count ≤ 5,000/mm³ (except mantle cell lymphoma with a leukemic
phase)

- Platelet count ≥ 50,000/mm^3

- Bilirubin ≤ 2.0 mg/dL

- AST and ALT ≤ 2.5 times upper limit of normal (ULN) (4 times ULN if liver involvement
with NHL)

- Creatinine ≤ 2.0 mg/dL

- Not pregnant or nursing

- Negative pregnancy test

- Fertile male and female patients must use effective contraception during study

- No serious nonmalignant disease

- No active infection

- No peripheral neuropathy ≥ grade 2 within past 14 days

- No myocardial infarction within the past 6 months

- No New York Heart Association class III or IV heart failure

- No uncontrolled angina pectoris

- No severe uncontrolled ventricular arrhythmias

- No EKG evidence of acute ischemia or active conduction system abnormalities

- Any EKG abnormality must be documented as not medically relevant

- No hypersensitivity to bortezomib, boron, or mannitol

- No known anaphylaxis or immunoglobulin E-mediated hypersensitivity to murine proteins
or any component of rituximab (including polysorbate 80 and sodium citrate dehydrate)

- No known infection or exposure to HIV

- No serious psychiatric or medical illness that would preclude study participation

- No active hepatitis B infection

- No other primary malignancy requiring active treatment

- More than 4 weeks since prior significant traumatic injury

PRIOR CONCURRENT THERAPY:

- At least 3 weeks since prior and no concurrent radiotherapy

- More than 4 weeks since prior major surgery or open biopsy

- Other diagnostic surgery allowed

- More than 4 weeks since prior cytotoxic chemotherapy (6 weeks for nitrosoureas)

- At least 3 months since prior unconjugated monoclonal antibody therapy

- At least 10 weeks since prior radioimmunoconjugates or toxin immunoconjugates (e.g.,
iodine I 131 tositumomab [Bexxar] or ibritumomab tiuxetan [Zevalin])

- More than 2 weeks since prior investigational agent

- No prior bortezomib

- No concurrent systemic corticosteroid at greater than the equivalent dose of 20
mg/day of prednisone, unless for treatment of allergic reactions to CT scan dye

- No concurrent major surgery

- No other immunosuppressive agents, unless for treatment of allergic reactions to CT
scan dye

- No other concurrent antilymphoma agents

- No other concurrent investigational agent

- Concurrent participation in another nontreatment study allowed if it does not
interfere with participation in this study