1. 1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania.
2. 2Health Sciences Mass Spectrometry Core, University of Pittsburgh, Pittsburgh, Pennsylvania.
3. 3Mass Spectrometry and Proteomics Core, The University of Utah, Salt Lake City, Utah.
4. 4Department of Pharmacology and Chemical Biology University of Pittsburgh, Pittsburgh, Pennsylvania.
5. 5Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania.