NU6300 is a potent and selective inhibitor of Cyclin-Dependent Kinase 12 (CDK12), a key enzyme involved in transcription and DNA damage response. It is primarily used in medicinal chemistry and oncology research to investigate CDK12's role in tumor progression, RNA splicing, and cellular signaling pathways. Researchers apply NU6300 in preclinical studies to assess its efficacy as a potential anticancer agent, particularly in ovarian, breast, and other CDK12-dependent cancers. It is also employed in biochemical assays to study enzyme kinetics, inhibition profiles, and downstream effects on gene expression, supporting the design of targeted therapies for complex diseases.