LY2608204 is primarily used in scientific research as a selective inhibitor of DNA-dependent protein kinase (DNA-PK), an enzyme involved in the repair of DNA double-strand breaks. Its main application lies in studies related to cancer biology and radiation response, where it is used to sensitize tumor cells to ionizing radiation or DNA-damaging chemotherapeutic agents. By inhibiting DNA-PK, LY2608204 impairs the non-homologous end joining (NHEJ) repair pathway, making it a valuable tool in exploring combination therapies that enhance the effectiveness of existing cancer treatments. It is not used clinically but serves as a critical compound in preclinical research to understand DNA repair mechanisms and develop novel anticancer strategies.