1. Department of Cell Biology, Utrecht University Medical School (T.L.B., H.L.R.-G., L.A.C.v.d.B., D.G.d.R.), 3584 CX Utrecht, The Netherlands
2. Cancer Center, University of Illinois College of Medicine (H.K.), Chigaco, Illinois 60607-7173
3. the Departments of Urology (T.M.T.W.L.), Academic Hospital Utrecht, 3584 CX Utrecht, The Netherlands
4. and Radiotherapy (I.S.G., D.H.R.), Academic Hospital Utrecht, 3584 CX Utrecht, The Netherlands
5. Program in Molecular Biology, Memorial Sloan-Kettering Cancer Center (A.K.), New York, New York 10021