Updated project metadata. 1. Sensitivity of FASP was tested using SDS lysates from HeLa cells and mouse brain. Peptides were analyzed using a QExactive HF-X instrument. We found that FASP allows effective processing samples at the low and sub-microgram range. 2. Whole cell lysates of Hela cells were processed with FASP using single or double, consecutive or successive, digestion with LysC or trypsin. The generated peptides were analyzed using a LTQ-Orbitrap mass spectrometer. The results show that short digestion times apparently do not affect the number of identified proteins.