Originally developed as a cancer drug, DeltaRex-G (formerly named Rexin-G, Mx-dnG1) is a tumor targeted retrovector encoding a cytocidal CCNG1 inhibitor gene which inhibits cyclin G1 expression, and consequently, blocks the cancer cell cycle in G0-G1 phase, aborting the cell cycle and resulting in cell death via the apoptosis-mediated pathway (Morse et al., 2021; Chawla et al., 2019). The gene discussed is CCNG1; the disease is cancer.