1. Natural Products Research Laboratories, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
2. Pharmacological Institute, College of Medicine, National Taiwan University, No. 1, Jen-Ai Road, Sec. 1, Taipei, Taiwan
3. Division of Medicinal Chemistry and Natural Products, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7568
4. University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030
5. Center for Molecular Medicine and Graduate Institute of Cancer Biology, China Medical University and Hospital, Taichung, Taiwan 404
6. Department of Biological Chemistry and Department of Developmental & Cell Biology, University of California, Irvine, California 92697-4037