KH-CB20, an E/Z mixture, is a potent and selective inhibitor of CLK1 and the closely related isoform CLK4 , with an IC 50 of 16.5 nM for CLK1 . KH-CB20 can also inhibit DYRK1A ( IC 50 =57.8 nM) and CLK3 ( IC 50 =488 nM) In Vitro KH-CB20 shows selectivity for CLK1 (IC 50 =16.5 nM) over DYRK1A (IC 50 =57.8 nM) and CLK3 (IC 50 =488 nM). MCE has not independently confirmed the accuracy of these methods. They are for reference only. Form:Solid IC50& Target:CLK1 16.5 nM (IC 50 ) DYRK1A 57.8 nM (IC 50 ) CLK3 488 nM (IC 50 )