GVHD PROPHYLAXIS: Patients receive mycophenolate mofetil PO three times daily (TID) on days 0-30, then BID until day 40, and cyclosporine PO BID on days -3 to 96, with a taper until day 150. Patients also receive sirolimus PO on days -3 to 150, with a taper until day 180.