TP53 and cancer: Many OV agents are genetically modified to limit replication within cancer cells while prohibiting replication in normal cells. The signaling pathways that are targeted comprise those that respond to hypoxia and include RB/E2F/p16, p53, protein kinase R (PKR), estimated glomerular filtration rate (EGFR), Ras, Wnt, apoptosis pathways, or interferon (IFN) and other innate immune-signaling pathways.15