TNFSF10 and neoplasm: Procaspase-3 activator 1 (PAC-1) directly activates procaspase-3, a key executioner of apoptosis, and synergizes with pro-apoptotic agents, such as TRAIL, to amplify tumor cell death (Ashkenazi, 2008; Aziz et al., 2010; Reed, 1999; Peterson et al., 2009).