Inclusion Criteria:

- Previously treated or relapsed follicular lymphoma. One prior therapy required.

- Bi-dimensionally measurable disease with at least one lesion measuring > 2.0 X 2.0cm
by CT scan or evaluable disease.

- CD20+ at time of diagnosis or subsequently.

- Platelet count > 100,000/uL, ANC > 1000/uL.

- Transaminases less than two-fold normal range.

- Adequate renal function defined as <1.5 X upper limit of normal

- HAMA negative

- ECOG performance status 0, 1, 2.

- Female subject is either post-menopausal or surgically sterilized or willing to use
an acceptable method of birth control (i.e., a hormonal contraceptive, intra-uterine
device, diaphragm with spermicide, condom with spermicide, or abstinence) for the
duration of the study.

- Male subject agrees to use an acceptable method for contraception for the duration of
the study.

- Negative Hepatitis profile screening

Exclusion Criteria:

- Myocardial infarction within 6 months prior to enrollment or has New York Heart
Association (NYHA) Class III or IV heart failure (see section 8.4), uncontrolled
angina, severe uncontrolled ventricular arrhythmias, or electrocardiographic evidence
of acute ischemia or active conduction system abnormalities. Prior to study entry,
any ECG abnormality at Screening has to be documented by the investigator as not
medically relevant.

- Patient has hypersensitivity to boron or mannitol.

- Greater than 25% of the intratrabecular marrow space involved by lymphoma in bone
marrow biopsy specimens

- Hypocellular bone marrow (≤15% cellularity or marked reduction in bone marrow
precursors).

- Prior myeloablative therapy.

- History of failed stem cell collection.

- Prior radiotherapy to fields encompassing more than 25% of the blood-forming marrow.

- Prior chemotherapy, biologic therapy, radiation therapy or steroid therapy for NHL
within three weeks prior to screening procedures. Six weeks for nitrosureas.
Subjects receiving low doses of steroids for non-neoplastic indications may enter the
study ("low dose steroids" is defined as ≤10 mg of prednisone or equivalent per day).

- Prior Radioimmunotherapy or bortezomib.

- Prior malignancy other than lymphoma, except for adequately treated basal cell or
squamous cell skin cancer, in situ uterine cervical cancer, or other cancer for which
the subject has been disease-free for five years.

- Evidence of active infection requiring intravenous antibiotics at the time of study
enrollment.

- Known HIV infection.

- Known brain or leptomeningeal metastases.

- Active obstructive hydronephrosis.

- Known Type I hypersensitivity or anaphylactic reactions to murine proteins or any
component of the Iodine I 131 tositumomab therapeutic regimen.

- Female subject is pregnant or breast-feeding. Confirmation that the subject is not
pregnant must be established by a negative serum pregnancy test result obtained
during screening. Pregnancy testing is not required for post-menopausal or
surgically sterilized women.

- Patient has received other investigational drugs with 14 days before enrollment

- Serious medical or psychiatric illness likely to interfere with participation in this
clinical study.

- Patient has Grade 2 peripheral neuropathy within 14 days before enrollment.