1. I. The, G. S. Cowley, S. Reginald, I. K. Hariharan, A. Bernards, Massachusetts General Hospital Cancer Center and Harvard Medical School Building 149, 13th Street, Charlestown, MA 02129, USA.
2. G. E. Hannigan and J. F. Gusella, Molecular Neurogenetics Unit, Massachusetts General Hospital and Harvard Medical School Building 149, 13th Street, Charlestown, MA 02129, USA.
3. Y. Zhong, Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.