Peptide differential display of serum-free conditioned medium from cancer cell lines

Conditioned medium (CM) from cultured cells is a source for screening small peptides of therapeutic or diagnostic value in cancer research. Mass spectrometry has recently enabled the profiling of peptides present in biological samples. We report a single-step extraction method to increase a chance to discover small peptides with a starting volume of 750 μl of serum-free CM. In combination with proteinchip mass spectrometry, our protocol will contribute to the discovery of target peptides.