AIM: To investigate the effects of Msx2 on lens epithelium cell cycle, and evaluate the changes of the proliferation, apoptosis of lens epithelium cells.METHODS: Mice lens epithelium cells were cultured and transfected with pEGFP-Msx2 and control. Msx2-de?cient mice (Msx2^-/-) lens tissue were isolated. Lens tissue and transfected cells were prepared for mRNA extraction using Trizol reagent. CyclinD1 and Prox1 expression were evaluated by real-time RT-PCR. BrdU incorporation and apoptosis rate were investigated by immunofluorescence and flow cytometry analysis.RESULTS: After transfected with pEGFP-Msx2, lens epithelium cells failed to incorporate BrdU and anti-phospho-histone-3 immunofluorescence failed to detect cell nuclei which GFP were positive. Msx2 over expression resulted in increasing apoptosis rate in lens epithelium cells. CyclinD1 and Prox1 expression increased significantly in Msx2 knockout mice by real-time RT-PCR quantization and CyclinD1 expression decreased significantly in Msx2 overexpressed cell.CONCLUSION:Msx2 has the effect of inhibiting proliferation and differentiation, triggering apoptosis on mice lens epithelium cells.