1. Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
2. Molecular Targets Program, Center for Cancer Research, NCI−Frederick, NIH, Frederick, Maryland 21702, United States
3. Developmental Therapeutics Branch, Laboratory of Molecular Pharmacology, NCI, NIH, Bethesda, Maryland 20892, United States
4. Chemical Biology Laboratory, Center for Cancer Research, NCI−Frederick, NIH, Frederick, Maryland 21702, United States
5. School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia
6. Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
7. Natural Products Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, Frederick, Maryland 21702, United States