The purpose of this study is to evaluate the effectiveness and safety of combining bortezomib (Velcade) with rituximab, fludarabine, mitoxantrone, and dexamethasone in treating patients with follicular cell lymphoma.

Inclusion Criteria:

• Diagnosis of grade 1-3 follicular lymphoma with persistent, relapsed, or refractory disease to at least one prior regimen.
• No prior bortezomib therapy.
• Voluntary written informed consent.
• Female subject is either post-menopausal or surgically sterilized or willing to use an acceptable method of birth control.
• Male subject agrees to use an acceptable method for contraception for the duration of the study therapy.
• 18 years of age or older.
• AST, ALT, total bilirubin < 3 times the upper limit of normal unless documented by the treating physician to be secondary to underlying lymphoma.
• ECOG performance status 0-2.

Exclusion Criteria:

• Platelet count of < 50,000 within 14 days before enrollment unless documented by the treating physician to be due to the disease.
• Absolute neutrophil count of < 1000 within 14 days before enrollment unless documented by the treating physician to be due to disease.
• Estimated or measured creatinine clearance of less than 30 ml/min within 14 days before enrollment.
• ≥Grade 2 peripheral neuropathy within 14 days before enrollment.
• Myocardial infarction within 6 months prior to enrollment or has New York Hospital Association (NYHA) Class III or IV heart failure, uncontrolled angina, severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence of acute ischemia.
• Patient has hypersensitivity to boron, mannitol or any drug included in the current protocol.
• Female subject is pregnant or lactating.
• Received other investigational drugs for this disease within 14 days of enrollment
• Serious medical or psychiatric illness likely to interfere with participation in this clinical study.
• Known HIV+ status.
• Cardiac ejection fraction less than 35% at study entry measured by echocardiogram, MUGA or cardiac MRI.