Inclusion Criteria:

1. Histology: biopsy-proven mantle cell lymphoma (MCL).

2. Prior therapy: both newly diagnosed patients and relapsed or refractory patients who
have received one prior therapy are eligible. Patients who have previously received
high-dose chemotherapy with peripheral stem cell support are eligible. Newly
diagnosed patients are eligible for the Phase II portion of the study only.

3. Presence of at least one lymph node evaluable or mass measurable for response.

4. Platelets > 75,000/µL and absolute neutrophil count (ANC) > 1,000/µL within 14 days
of study registration (unless the treating physician deems the neutropenia is related
to bone marrow involvement, then an ANC of > 750/mm3 is allowed).

5. Serum creatinine ≤ 2.0 mg/dL within 14 days of study registration.

6. ECOG performance of 0, 1, or 2.

7. Age greater than or equal to 18 years.

8. Recovery from any previous treatment therapy.

9. Females of childbearing potential (FCBP)† must have a negative serum or urine
pregnancy test with a sensitivity of at least 50 IU/mL within 10 14 days prior and
again within 24 hours of starting lenalidomide. FCBP must either commit to continued
abstinence from heterosexual intercourse, or begin TWO acceptable methods of birth
control (one highly effective method and one additional effective method AT THE SAME
TIME) at least 28 days before she starts taking lenalidomide. FCBP must also agree
to ongoing pregnancy testing. Men must agree not to father a child and agree to use
a latex condom (NOTE: for patients who have latex allergies or whose partner(s) have
latex allergies, alternatives will be discussed) during sexual contact with an FCBP,
even if they have had a successful vasectomy. FCBP must agree to use a method of
contraception that is acceptable to the treating investigator until 12 months after
their last dose of rituximab. See Appendix E ("Risks of Fetal Exposure, Pregnancy
Testing Guidelines, and Acceptable Birth Control Methods") and Section 3.1 for more
information.

10. Ability to understand and willingness to sign a written informed consent document.

Exclusion Criteria:

1. Peripheral neuropathy > CTCAE grade 2.

2. Pregnant or breastfeeding females. (Lactating females must agree not to breastfeed
while taking lenalidomide.)

3. Thrombolic or embolic events (such as a cerebrovascular accident, including transient
ischemic attacks) within the past 6 months.

4. Pulmonary hemorrhage/bleeding event less than or equal to CTCAE grade 2 within 28
days of the first dose of study drug.

5. Any other hemorrhage/bleeding event less than or equal to CTCAE grade 3 within 28
days of the first dose of study drug

6. Known brain metastasis. Patients with neurological symptoms must undergo a CT
scan/MRI of the brain to exclude brain metastasis.

7. Central nervous system (CNS) involvement by lymphoma at time of enrollment.

8. Other medical conditions that would potentially interfere with patient participation
in this trial.

9. A second malignancy, other than basal cell carcinoma of the skin or in situ carcinoma
of the cervix, unless the tumor was treated with curative intent at least 2 years
previously.

10. Previous evidence of hypersensitivity to bortezomib, boron, mannitol, thalidomide, or
rituximab (true anaphylaxis, not a rituximab-infusion reaction).

11. Known human immunodeficiency virus (HIV) infection or chronic hepatitis A, B, or C.
Patients who are HIV positive or who are positive for chronic hepatitis A, B, or C
will be excluded due to increased risk for bone marrow suppression and other
toxicities.

12. Active, clinically serious infection > CTCAE grade 2. Patients may be eligible upon
resolution of the infection.

13. Evidence or history of bleeding diathesis or coagulopathy.

14. Major surgery, open biopsy, or significant traumatic injury within 28 days of the
first dose of study drug.

15. Use of any other standard chemotherapy, radiation therapy, or experimental drug for
the treatment of MCL within 28 days of starting treatment.

16. Any condition that impairs a patient's ability to swallow whole pills. Impairment of
gastrointestinal function (GI) or GI disease that may significantly alter the
absorption of lenalidomide (e.g., ulcerative disease, uncontrolled nausea, vomiting,
diarrhea, malabsorption syndrome, or small bowel resection).

17. Patients with grade 3/4 cardiac problems, as defined by the New York Heart
Association (NYHA) criteria:

- History of uncontrolled or symptomatic angina

- History of arrhythmias requiring medications, or clinically significant, with
the exception of asymptomatic atrial fibrillation requiring anticoagulation

- Myocardial infarction < 6 months from study entry

- Uncontrolled or symptomatic congestive heart failure

- Ejection fraction below the institutional normal limit

- Any other cardiac condition that, in the opinion of the treatment physician,
would make this protocol unreasonably hazardous for the patient

18. Uncontrolled hypertension (systolic blood pressure [BP] > 180 or diastolic BP > 100mm
Hg) or uncontrolled cardiac arrhythmias.

19. Any prior use of lenalidomide.