1. Metabasis Therapeutics, Inc., 11119 North Torrey Pines Road, La Jolla, California 92037, United States
2. Vertex Pharmaceuticals Inc., 3215 Merryfield Row, San Diego, California 92121, United States
3. University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States
4. School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, P. R. China