1. From the Department of Internal Medicine (Cancer Research), West German Cancer Center, University Medical School, Essen, Germany; Department of Hematology and Oncology, Charité, Campus Berlin-Buch, Humboldt University, Berlin, Germany; Department of Clinical Research, Oncology-New Technology, Rhône-Poulenc Rorer, Cologne, Germany; and Department of Pharmacology and Experimental Therapeutics, Grace Cancer Drug Center, Roswell Park Cancer Institute, Buffalo, NY.