Western blots were done after semi-dry transfer of the proteins to a nitrocellulose membrane as described [25] . Mouse a-casein protein was detected using a rabbit-anti a-casein antiserum (Santa Cruz Biotechnology sc-98699) and a horse-radish-peroxidase linked goat anti-rabbit serum (Cell Signalling Technologies #7074). Mouse b-casein protein was detected using a goat-anti b-casein antiserum (Santa Cruz Biotechnology sc-17969) and a horse-radish-peroxidase linked rabbit anti-goat serum (Jackson Immuno-Research). Mouse grp78/BiP protein was detected using a goat-anti grp78/BiP antiserum (Santa Cruz Biotechnology sc-1051) and a horse-radish-peroxidase linked rabbit anti-goat serum. All antibodies were used at a dilution of 1:1000.