The Assay Development Working Group (ADWG) of the CPTAC Program is currently drafting a document to propose best practices for generation, quantification, storage, and handling of peptide standards used for mass spectrometry-based assays, as well as interpretation of quantitative proteomic data based on peptide standards. The ADWG is seeking input from commercial entities that provide peptide standards for mass spectrometry-based assays or that perform amino acid analysis. Parties interested in providing input into the best practices document should contact the Office of Cancer Clinical Proteomics Research at cancer.proteomics@mail.nih.gov by 09 March 2015.