2D-DIGE gel images. (A) Representative 2D image (scanned using an Ettan DIGE Imager, GE Healthcare) of a Cy2-labeled mixture of the 48 protein extracts (50 μg of each). The total number of polypeptide spots observed and matched is 928 (only polypeptide spots present in at least 75% of analytical images were retained). (B) False-colored representation of 2D images issued from a single gel: Cy3 and Cy5 images correspond to analytical samples and Cy2 to the internal standard. Superimposition of the 3 images colored by ImageMaster 2D Platinium Version 6.0 software (GE Healthcare) allows to represent overexpressed polypeptide spots in S samples in red and overexpressed polypeptide spots in US samples in green.