About the Authors

David G. Covell

covelld@mail.nih.gov

Affiliation Screening Technologies Branch, Developmental Therapeutics Program, National Cancer Institute, Frederick, Maryland, United States of America

Competing Interests

The author has declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: DGC. Performed the experiments: DGC. Analyzed the data: DGC. Contributed reagents/materials/analysis tools: DGC. Wrote the paper: DGC.