KU-55933 is primarily used in biomedical research as a selective inhibitor of the ATM (ataxia telangiectasia mutated) kinase, a key protein involved in the cellular response to DNA damage. It is widely applied in studies related to DNA repair mechanisms, cell cycle regulation, and apoptosis. By inhibiting ATM kinase activity, KU-55933 helps researchers dissect signaling pathways activated by DNA double-strand breaks. This compound is especially valuable in cancer research, where it is used to sensitize tumor cells to ionizing radiation and chemotherapeutic agents. Its ability to suppress ATM-mediated DNA repair enhances the effectiveness of treatments that induce DNA damage, making it a useful tool for exploring combination therapies. KU-55933 also aids in the study of neurodegenerative diseases linked to DNA repair deficiencies, such as ataxia-telangiectasia. Due to its high selectivity, it allows for precise modulation of ATM activity without significantly affecting related kinases like DNA-PK or PI3K, reducing off-target effects in experimental models.