['To determine serum insulin levels, expression and phosphorylation of InsR, IRS-1 and Akt in endometrial cancer (EC) tissues, and to explore the correlation between them. To investigate if insulin-induced mitogenic and anti-apoptotic effects are PI3K-dependent in EC cells.', 'Serum insulin levels were measured by radioimmunoassay. We performed RT-PCR and western blotting to evaluate the expression and activation of key proteins of PI3K/Akt pathway in 63 EC tissues. The proliferation and apoptosis rates were determined with MTT, BrdU and annexin V/PI assays.', 'Serum insulin levels and InsR, IRS-1 and Akt expression and phosphorylation were significantly elevated in patients with EC compared to those without EC. Additionally, levels of p-InsR, p-IRS-1, and p-Akt were significantly higher in patients with high-grade, advanced stage, deep myometrial invasion, and lymph-node metastasis. The expression and activation of InsR, IRS-1, and p-Akt were positively related with the levels of serum insulin. The insulin-induced mitogenic and anti-apoptotic effects in EC cells were blocked when cells were pre-incubated with LY294002. Ishikawa 3-H-12 cells showed increased p-Akt levels after treatment with insulin at 10(-8)M for 15min. The insulin-induced Akt activation was inhibited by LY294002 in a dose-dependent manner.'] Are mitogenic and anti-apoptotic effects of insulin in endometrial cancer phosphatidylinositol 3-kinase/Akt dependent?