AIM: To investigate the regulation of Eaf2 protein in mouse lens cells apoptosis induced by ultraviolet (UV) radiation.METHODS: An eye of Eaf2 gene knockout mice or normal control mice was exposed to UV radiation, and the other one was non-exposed. All of lenses were analyzed by TUNEL and caspase 3 activity assays to determine the difference of the apoptosis induced by UV radiation. In addition, exposed and non-exposed lenses were analyzed by quantified p53 expression and real-time reverse transcription-polymerase chain reaction (RT-PCR) of Bax, Bid, Apaf-1, Puma and Noxa, to compare Eaf2 gene knockout mice and normal control mice.RESULTS: UV radiation caused apoptosis of lens cells in normal control mice and Eaf2 knockout mice. Activity of caspase 3 was significantly higher in normal control mice than Eaf2 knockout mice. Expression of p53 protein was significantly higher in lenses exposed to UV radiation than nonexposed lenses, but was similar between Eaf2 gene knockout mice and normal control mice in the same UV condition. After exposing to UV radiation, the analysis of real-time RT-PCR demonstrated that mRNA levels of Puma and Noxa were significantly higher in lenses of normal control mice than Eaf2 gene knockout mice, and that mRNA levels of Bax, Bid and Apaf-1 were not significantly different between gene knockout mice and normal control mice.CONCLUSION: Eaf2 increases lens cells apoptosis induced by ultraviolet radiation. And Eaf2 up-regulates expression of the Puma and the Noxa to act on lens cells apoptosis after UV radiation.