biological role radiation response modifier Radiation response modifiers are agents that alter tumor or normal tissue response to radiation, such as radiation sensitizers and radiation protectors. Citrin DE, Mitchell JB. Altering the response to radiation: sensitizers and protectors. Semin Oncol. 2014 Dec;41(6):848-59. doi: 10.1053/j.seminoncol.2014.09.013. Epub 2014 Oct 7. PMID: 25499642; PMCID: PMC4270009.