Used as a potent and selective inhibitor of cyclin-dependent kinases (CDKs), particularly CDK4 and CDK6, this compound plays a key role in cancer research. It is widely applied in studies targeting cell cycle regulation in tumor cells, especially in hormone receptor-positive, HER2-negative breast cancer. By blocking CDK4/6 activity, it prevents phosphorylation of the retinoblastoma (Rb) protein, leading to cell cycle arrest in the G1 phase and inhibition of uncontrolled cell proliferation. Its application extends to preclinical models for evaluating antitumor efficacy, pharmacokinetics, and combination therapies with hormonal agents or other targeted drugs. Due to its well-defined mechanism, it serves as a critical tool compound in oncology drug discovery and molecular pharmacology studies.