GRAFT-VERSUS-HOST-DISEASE (GVHD) PROPHYLAXIS: Patients receive mycophenolate mofetil (MMF) PO every 12 hours on days 0-27 (related donor recipients) or every 8 hours on days 0-96 with taper on day 40 (unrelated donor recipients). Patients also receive cyclosporine IV or PO every 12 hours on days -3 to 56, followed by taper on days 57-180 (related donor recipients) or on days -3 to 100, followed by taper on days 101-177 (unrelated donor recipients).