Reducing 2-DGE of rennet casein fraction from heat-treated milk visualised by colloid Coomassie Brilliant Blue G-250 staining. The conditions of the 2-DGE were as described in Figure 1 legend, except that this gel was run at reducing conditions as described in Materials and Methods. The sample analysed in Figures 1 and 2 was from the same individual cow. 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 reduced gels. The positions of major caseins assigned according to [31] are indicated in white.