Cardiac fibroblasts were cultured in either low glucose (5 mM) or high glucose (25 mM) for the designated time and cell lysates were collected and subjected to Western blot analysis for phospho-ERK and total ERK. A) Basal ERK phosphorylation was lower in fibroblasts treated with high glucose for 20 min (0.13±0.06 fold, p<0.05), 60 min (0.08±0.42 fold, p<0.001), and 4 h (0.20±0.16 fold, p<0.05). Data are representative of duplicate wells from 4 separate CF preparations (n=4). Statistical significance (p<0.05) between groups was determined by one-way ANOVA.