Cell-permeable. Flavopiridol is a synthetic flavonoid compound used as an anticancer agent. It is a serine/threonine kinase inhibitor that broadly targets cyclin-dependent kinases (CDKs), including the cyclin 9/cyclin T complex (pTEF-b), preventing activation of RNA polymerase II. Flavopiridol initiates cell cycle arrest and p53-independent apoptosis through down-regulation of Mcl-1 and X-linked inactivator of apoptosis (XIAP). MW: 401.84. Purity ≥98% by HPLC