Stem cells are the cells from which all blood cells develop. If you respond to the first 2 cycles of bortezomib/rituximab, you will then have some of your stems cells collected. You will have to sign a separate consent form that describes this procedure and its risks. After the stem cell collection, 1 cycle of cladribine, cyclophosphamide, and rituximab will be given. Cladribine will be given through a vein once a day over 2 hours on Days 1-5. Cyclophosphamide is taken by mouth, twice a day on Days 1-5, and rituximab is given through a vein once a week for 4 weeks.