Myc proteins are transcription factors that activate expression of many pro-proliferative genes through binding enhancer box sequences (E-boxes) and recruiting histone acetyltransferases (HATs). Myc is thought to function by upregulating transcript elongation of actively transcribed genes through the recruitment of transcriptional elongation factors. It can also act as a transcriptional repressor. By binding Miz-1 transcription factor and displacing the p300 co-activator, it inhibits expression of Miz-1 target genes. In addition, myc has a direct role in the control of DNA replication. This activity could contribute to DNA amplification in cancer cells.