1. Laboratory of Cell Biology, Center for Cancer Research (CCR), National Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, MD 20892, USA
2. University of British Columbia, Vancouver, British Columbia, Canada
3. Laboratory of Biochemistry and Molecular Biology, CCR, NCI, NIH, Bethesda, MD 20892, USA
4. Frederick National Laboratory for Cancer Research, Frederick, MD, USA