The cell proliferation induced by tamoxifen was inhibited by the MEK inhibitor U0126 and PI3K inhibitor LY294002 (Fig. 6B), suggesting that both the MAPK/ERK and PI3K/Akt pathways were involved in E2 and tamoxifen stimulated cell growth in endometrial cancer cells. This evidence concerns the gene AKT1 and endometrial cancer.