1. State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, CAS, 555 Zuchongzhi Road, Shanghai 201203, China, Laboratory of Antiviral Drug Mechanisms, SAIC−Frederick, Screening Technologies Branch, DTP, DCTD, National Cancer Institute at Frederick, Frederick, Maryland 21702, and Department of Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089