MYC and cancer: In addition to drive cancer initiation, MYC is also responsible for its maintenance: in several MYC-driven mouse tumor models, blocking MYC activity elicits tumor regression by promoting growth arrest and apoptosis and inducing cell differentiation, such as in sarcoma and hepatocellular cancer (Felsher and Bishop, 1999; Jain et al., 2002; Pelengaris et al., 2002; Shachaf et al., 2004).