1. NCI RAS Initiative, Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
2. Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94143, United States
3. Small Molecule Discovery Center, University of California, San Francisco, California 94143, United States
4. Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, California 94158, United States