RO-9187 is a potent and selective inhibitor of cyclin-dependent kinases (CDKs), particularly CDK9, which plays a key role in transcriptional regulation. Its primary application lies in cancer research, where it is used to study the inhibition of tumor cell proliferation by disrupting RNA polymerase II-dependent transcription. Due to its ability to induce apoptosis in leukemia and other cancer cell lines, RO-9187 serves as a valuable tool compound in preclinical studies exploring CDK-targeted therapies. It is also used to investigate the role of CDK9 in viral replication, including HIV, where CDK9 is a component of the positive transcription elongation factor b (P-TEFb). This makes RO-9187 relevant in antiviral research as well.