1. Natural Products Laboratory, Worldwide Medicinal Chemistry, Pfizer Worldwide Research and Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
2. Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute, National Institutes of Health, 9609 Medical Center Drive, Bethesda, Maryland 20892, United States
3. Novartis Institutes for BioMedical, Research, Inc., 250 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
4. Pfizer Oncology, 401 N. Middletown Road, Pearl River, New York 10965, United States