Isotopically labeled standards for proteomic measurements can be prepared chemically. This can be achieved at the peptide or protein level by solid phase synthesis or recombinant gene expression, respectively. To aid the synthesis of stable isotope-labeled peptides, CIL offers an array of protected amino acids and preloaded resins. For the expression of stable isotope-labeled proteins, we offer media as well as cell-free protein expression reagents and kits from CellFree Sciences. CIL also offers select full-length proteins (e.g., ApoA-I, IGF1, and ubiquitin) for use in bottom-up LC-MS experiments. The synthesis/expression products are briefly described and referenced on their associated page.