Author information:
(1)Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, 
National Cancer Institute, Building 37, Room 6114, Bethesda, MD 20892, USA.
(2)Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, 
Ashburn, VA 20147, USA.
(3)Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, 
National Cancer Institute, Building 37, Room 6114, Bethesda, MD 20892, USA. 
Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, 
Ashburn, VA 20147, USA. wuc@janelia.hhmi.org.