E2Fs transcription factors can control transcription of genes involved in cellular proliferation,differentiation and apoptosis.So far,in mammals,E2F family has seven identified members,E2F-1,E2F-2,E2F-3,(E2F-4),E2F-5,E2F-6 and E2F-7,and each of has special function.Recently,many investigations have demonstrated that E2F-1 has an apparently unique capability to induce apoptosis,and its functions relate to P53、P73、APAF-1、Caspase3 、Caspase7、BcL-2 family members、DIP、SIVA 、NF-?B factor and so on.According to the dependence on P53,molecular mechanisms of E2F-1 induced apoptosis are classified as both P53-dependent and P53-independent.Therefore,(E2F-1) is a novel target site of tumor genetherapy.