This way of comparing performances is misleading, considering that the high abundant proteins in the plasma are also present in many different isoforms that appear as different spots in a 2D gel. Therefore, a higher number of spots visible on a gel could be indicative of an incomplete or partial depletion rather then of a more efficient depletion. Conversely,IMB5046 it is essential to identify the proteins and classify them according to protein families in order to compare the real capacity of the depletion or the enrichment methods, to remove the highly abundant proteins or enrich the low abundant ones. For these reasons, in order to compare depletion and enrichment methods, we have decided to use a gel-free approach. The aim of this study was to determine which method between HAPs depletion and LAPs enrichment provides the best overall results in terms of number of identified proteins, protein coverage and enhanced sensitivity limit. In particular, for the first time, we compared the results obtained using ProteoMiner to those obtained using ProteoPrep20, which is currently the deepest depletion spin column kit commercially available. The most straightforward result of this study,ESI-05 as can be deduced from Table 1, is the lower efficacy of the ProteoMiner approach in terms of total number of proteins identified, while the immunodepletion and the multi-step depletion approaches led to a similar number of positive identifications. The same result was found for the total number of peptides. What is striking to notice is the number of proteins or protein groups that are identified with only one significant peptide. In average, for about 30% of the proteins, only one specific peptide was sequenced. These results are in line with what has been reported in other studies, where the contribution of single peptide identifications is also quite large. Although the enrichment method led to a lower number of protein identifications, the protocol is much simpler and faster compared to the depletion approach and requires less sample manipulations. This advantage of the enrichment over the depletion protocol is evident when considering the number of contaminant proteins that were identified.