Figure 2.

Schematic model of E2F1 activation by HMGA2. Following HMGA2 overexpression, transcription through E2F1 sites switches from repression to activation through four steps: 1- HMGA2 binds to pRB, which is complexed with E2F1 and HDAC1 to form the active repression; 2- the interaction between HMGA2 and pRB displaces HDAC1; 3- in the absence of HDAC1, the histone acetylase enzymes are recruited and, by acetylating histones, relieve transcriptional repression; 4- histone acetylases also acetylate E2F1 causing the stabilization of its "free" active form.