ATM and cancer: Many of these pathways depend on ATM and/or p53 to enforce tumor suppressive anti-cancer barriers to limit proliferation in response to, and in the presence of, DNA damage (Norbury and Zhivotovsky, 2004; Bartkova et al., 2005; Gorgoulis et al., 2005; Bartkova et al., 2006; Di Micco et al., 2006; Vousden and Lane, 2007; Sherman et al., 2011; Roos and Kaina, 2013).