 The purpose of this research study is to test the safety and effectiveness of VELCADE in the treatment of acute graft-versus-host disease GVHD that has not responded to steroids or has worsened when the steroid dose was decreased. VELCADE is a drug that inhibits certain immune reactions that happen when lymphocytes encounter foreign substances. We are doing this research to determine if VELCADE may be useful in treating GVHD. 