Flavopiridol is a broad-spectrum, ATP-competitive inhibitor of cyclin-dependent kinases used in research to probe cell-cycle regulation and kinase signaling. It inhibits CDK1, CDK2, and CDK4 with reported IC50s of 30 nM, 170 nM, and 100 nM, respectively. Supplied as a solid research reagent with documented solubility and storage recommendations.