Mnt: master regulator of the Max network.

Recent findings indicate that we should rethink how Myc oncoproteins transactivate their target genes. It appears that Mnt, a transcription factor that mediates transrepression at Myc's E-boxes, plays a crucial role in keeping the cell cycle in check. By removing Mnt, either via conventional knockout techniques or via RNA interference, cells become hyper-proliferative, susceptible to apoptosis and can be transformed by Ras--all hallmarks of Myc overexpression. These findings indicate that Myc's ability to function as an oncogene may rely, at least in part, on its ability to effectively antagonize Mnt's transrepression and tumor suppressor functions.