**4. Regulation of E2F-1 by post-translational modifications**

Another mode of E2F regulation that fine-tunes cell cycle progression and DNA repair occurs at the post-translational level. Post-translational modifications identified in E2F-1 include phosphorylation, acetylation, methylation & ubiquitination. These modifications can exert either activating or inhibitory effects on E2F-1 transcriptional activity.
