Non-reducing 2-DGE of rennet casein fraction from heat-treated milk visualised by colloid Coomassie Brilliant Blue G-250 staining. A representative proteomic profile of the rennet casein fraction prepared from skimmed milk of one individual cow and separated in a 8–16% polyacrylamide gel at a pI gradient from 4 to 7. A total of 50 μg of protein was applied. The positions of protein spots referred to in Tables I and II are indicated by an arrow and by their identification number in the image analysis of the non-reducing gels.