 This is a research study designed to look at the biological effects of two drugs on leukemia cells. In this study, we are comparing the effects of drugs called corticosteroids when used alone or with another drug called rapamycin. Rapamycin is a drug that prevents the bodys immune system from working normally. It has been used for many years after kidney transplants to prevent rejection of the organ. Recent work suggests that rapamycin may also help treat leukemia and other cancers. 