BS-181 HCl is primarily used in research settings to study its potential as a selective inhibitor of CDK7, a cyclin-dependent kinase involved in cell cycle regulation and transcription. Its application is significant in cancer research, where it helps investigate the role of CDK7 in tumor growth and proliferation. By inhibiting CDK7, it provides insights into the mechanisms of cancer cell survival and may aid in the development of targeted therapies. Additionally, it is utilized in biochemical assays to understand the broader functions of CDK7 in cellular processes, including its impact on gene expression and RNA polymerase II activity.