About the Authors
Department of Epidemiology and Biostatistics, Center for Bioinformatics and Molecular Biostatistics, University of California, San Francisco, California, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: MRS. Performed the experiments: YX. Analyzed the data: YX. Contributed reagents/materials/analysis tools: MRS. Wrote the paper: YX MRS.