A10 cells were treated with vehicle (dH2O), high glucose, and/or EGCG at the indicated concentrations and times.
The cells were lysed in a lysis buffer, sonicated, placed on ice for 1 h, andcentrifuged at 16000 g for 30 min. The supernatants were stored at 70 C until use. After the protein concentrations had been
measured, the supernatants were mixed with Laemmli sample buffer,
boiled for 5 min, subjected to electrophoresis, and then transferred
electrophoretically onto nitrocellulose membranes. The transblots were
blocked overnight with 5% nonfat dry milk in PBS-T buffer (0.05%
Tween 20 in 10 mM phosphate-buffered saline) at 4 C with constant
shaking and then incubated with the ERK1/2 (1:1000) or phosphory-
lated ERK1/2 antibody (1:1000) in 5% nonfat dry milk in PBS-T buffer
for 1 h at room temperature. The primary antibody binding was then
probed by a peroxidase-labeled goat anti-rabbit IgG antiserum. The
signal was detected using chemiluminescence and developed on X-ray
film. The density of the bands was quantified by densitometry using
Quantiscan, as reported previously.
21,22