TP53 and cancer: Replication of the mutant Ad2 with E1B 19K deletion (dl250) was significantly reduced in normal cells secondary to rapid apoptosis induction in the presence of tumor necrosis factor-α (TNF-α), whilst the opposite occurred in cancer cells due to multiple defects in the apoptotic pathways (e.g., p53 mutation, Bcl-2 overexpression) [30] (Figure 2).