An inhibitor of cyclin-dependent kinases (Cdks; IC50s = ~100, ~100, ~100, and 300 nM for Cdk1, Cdk2, Cdk4, and Cdk7, respectively); inhibits TEFb (Ki = 3 nM); inhibits transcription of a CMV promoter in HeLa nuclear extract (IC50 = 34 nM), Tat-stimulated transcription of an HIV-1 promotor (IC50 = 7 nM), and HIV-1 replication in HEK239T cells (IC50 = <10 nM); induces apoptosis and cyclin D1 depletion and delays tumor growth in an HN-12 head and neck carcinoma mouse xenograft model at 5 mg/kg; suppresses synovial hyperplasia and joint destruction in a mouse model of collagen-induced arthritis