FIGURE 4.

SPARC expression in pancreatic stromal cells is regulated by metabolic parameters. PS-1 cells were seeded at 5 × 10⁴ cells/well in 48-well plates and cultured for 24 h at the indicated concentrations of glucose and insulin, or for 48 h at the indicated concentrations of leptin. SPARC expression was then quantitated by Western blot and standardized to β-tubulin to control for loading variation. Equal protein was loaded (10 μg) in each well. Representative blots are shown in A, and mean relative SPARC expression (standardized to β-tubulin) ± S.E. is shown for glucose (B), insulin (C), and leptin (D). Quantitated data are pooled from 3–5 independent experiments, each with single data point for each treatment. p values indicate statistical analysis using one-way ANOVA.