Proteomic comparison of C3H and C57BL mouse livers before and after DDC treatment by 2D DIGE analysis and classification of differentially expressed proteins into function-based groups. (A) Liver homogenates were prepared from untreated mice (Control) or mice fed a DDC-containing diet for 3 mo. The liver proteins from the C3H and C57BL mice were labeled with the fluorescent dyes Cy3 (green) and Cy5 (red), respectively. The circled spots indicate differentially expressed proteins that were selected for identification by MS. (B) From an initial analysis of 80 selected gel spots, proteins that were identified as having significant expression differences (ratio greater than two) between the two mouse strains under basal conditions or after DDC treatment are shown. Note that PRDX6 is represented twice, reflecting the acidic and basic forms of the protein. (C) The proteins shown in B were classified into three groups based on their known functional properties.