RP-HPLC elution profiles of C57BL/6J (green) and SEG/Pas (blue) skimmed milks samples at 10 days of lactation. Clarified milk samples (100 μl; ca. 350 μg of proteins) were injected on a Jupiter C5 Reverse Phase column (300 Å pore size, 5 μm, 150 × 4.6 mm; Phenomenex, Paris, France). The elution was achieved by a two steps linear gradient: 100% A (TFA/H2O 1.1:1000 v/v) to 20% solvent B (TFA/CAN 1:1000 v/v) over 10 min followed by 37% solvent B to 60% over 45 min at a flow rate of 1ml/min. The column was kept at 40°C. Proteins showing a different behavior between mouse species are indicated in pink.