a-Casein Deficient Mice concentrated protein sample buffer was added. The samples were separated on a 10% polyacrylamide gel and stained with Coomassie Blue. Milk protein expression visible in the stained gel was then analysed on a Kodak Imaging Station using the Kodak 1D imaging software. Total protein extracts from tissues were isolated as described [23] . Briefly tissue fragments were dounced on ice at 100 mg/ml in a buffer containing 1% SDS, 1% NP-40 and 0.5% deoxycholic acid in 16 PBS supplemented with a broad spectrum proteinase inhibitor mix (SIGMA P-8340). The lysates were incubated on ice for 30 min. and then centrifuged at 4uC for 10 min. at 10000 g. The supernatants were then aliquoted and stored at 280uC.