Effect of ARA extract on PI3K/IRS-1 signaling pathway in 3T3-L1 cells. The cells were induced to differentiate into adipocytes with MDI medium with or without ARA (100, 200 and 500 mg/mL) for 8 days. The expression of PI3K and the phosphorylation of IRS-1 were analyzed by western blot. Relative density was calculated as the ratio of PI3K and IRS-1 expression to actin expression. Each value represents the mean ± S.D. (n = 3). *p < 0.05 vs. control. C: control, 100: ARA 100 μg/mL, 250: ARA 250 μg/mL and 500: ARA 500 μg/mL.