Inhibitors of DNA-PK or PARP individually can sensitize cancer cells to DNA-damaging agents (Willmore et al., 2004; Donawho et al., 2007; Penning et al., 2009; Amrein et al., 2011; Siddiqui-Jain et al., 2012; Davidson et al., 2012b). Here, PARP1 is linked to cancer.