Abstract: 【Abstract】 Objective To study the anti-cancer activities of Z-Leu-Leu-Leu-cho (MG132) against human endometrial carcinoma HEC-1B and Ishikawa cells and the potential of MG132 in human endometrial cancer therapy. Methods HEC-1B and Ishikawa cells were treated with MG132. Cell proliferation was assessed by MTT while cell apoptosis rate and cell-cycle distribution were assessed by flow cytometry. Results The proliferation of HEC-1B and Ishikawa cells was inhibited by MG132 and cell proliferation was significantly inhibited with the raised concentration of MG132 (P<0.01), Ishikawa cells were more sensitive than HEC-1B cells to MG132. MG132 could induce the apoptosis of HEC-1B and Ishikawa cells (P=0.000). Cell cycle analysis indicated that the percentage of HEC-1B cells was increased in G2 phase (P<0.05) while Ishikawa cells’ was increased in G1 and G2 phase (P<0.05). Conclusion Proteasome inhibitor MGl32 could inhibit the proliferation, promote cell apoptosis, and block the cell cycle of HEC-1B and Ishikawa cells. MG132 may be a potential treatment for endometrial cancer.