Benfluorene is a selective inhibitor of CDK1 (IC50 = 28.8 μM) and has P-glycoprotein-modulating properties (inhibitory activity ratio 9.5 at 7 μM). It weakly inhibits CDK5 (6% inhibition at 10 μM) with no effect on CDK2 and CDK4 (IC50 > 100 μM).
K. Brachwitz, et al.; J. Med. Chem. 46, 876 (2003).