Exposure to DNA-damaging agents and subsequent energy expenditures by a cell to repair DNA damage. Genotoxic stress elicits biochemical responses that either enhance cell survival or lead to cell death. These biochemical responses include DNA-damage-inducible repair and increasing expression of a variety of proteins by both transcriptional and post-transcriptional mechanisms. Genotoxic stresses frequently activate signal transduction pathways that originate in the cell membrane or cytoplasm, triggering similar phosphorylation cascades to those induced by the activation of cell-surface receptors. [ ]