Cartoon describing the multiple-enzyme digestion, filter-assisted sample preparation strategy (MED-FASP) from Wiesinski and Mann. A proteome is digested on top of a size-based filter device and peptides are then spun through the filter. Undigested sequences are retained above the filter because of their length. The process is repeated with various cleavage agents and several peptide pools are collected separately. The peptides are then analyzed by nLC-MS/MS separately and the resulting data is then combined either before or after the database search.