This session will provide an overview of the key discoveries - past and present - that make modern molecular biology, genomics possible, and that provide insights into molecular radiobiology and how it is used to modify radiosensitivity. The first part of the session will discuss laboratory and pre-clinical studies (PhD scientist speaker) and the second speaker (clinician MD PhD) will present and review clinical studies. Attendees should also come away with an understanding of modern molecular radiobiology for the purposes of better understanding translational research. At the conclusion of this activity, the learner will be able to do the following: 1. Summarize common molecular biology from DNA to proteins and response to radiation injury. 2. Discuss basic terminology and concepts associated molecular radiobiology and the commonly used assays to measure molecular damage and signaling pathways in laboratory and pre-clinical animal studies. 3. Describe the clinical approaches used to modify the radiation response by chemical and genetic modifications of radiation response with emphasis on PARP.