Figure 1: Experimental scheme of the procedures used for the screening of differentially expressed proteins. After enzymatic digestion, peptides were differentially stable isotope dimethyl-labeled and combined prior to desalting and fractionation. The quantitative shotgun analysis of proteome changes from clinical urine samples of normal and HCC patients was carried out by using HILIC-C18 peptide separation and nanoLC-MS/MS coupled with stable isotope dimethyl labeling.