1. Department of Chemical and Systems BiologyStanford University 269 Campus Dr., CCSR 3155 Stanford CA 94305 USA
2. Present address: Division of Chemistry and Chemical EngineeringCalifornia Institute of Technology Pasadena CA 91125 USA
3. Present address: Global Health Drug Discovery Institute Beijing 100192 China
4. Present address: Thermo Fisher Scientific Carlsbad CA 92008 USA
5. Department of Developmental BiologyStanford University 269 Campus Dr., CCSR 3155 Stanford CA 94305 USA
6. Department of ChemistryStanford University 269 Campus Dr., CCSR 3155 Stanford CA 94305 USA