We applied the quantitative proteomics approach to estimate the relative abundance of proteins in HepG2 cells treated by glutamine deprivation. Two independent cultured cell lysates, namely control and glutamine deprivation, were marked with iTRAQ labels and subjected to LC-ESI-MS/MS analysis. The tryptic peptides of two samples were labeled with mass 113 (control) and 119 (glutamine deprivation) isobaric iTRAQ tags.