KH-CB19 showed potent inhibition of CLK1 (IC50: 20 nM), and for the pure isomer KH-CB19, almost 100-fold selectivity against the CLK3 isoform. Treatment of resting cells with 10 μM KH-CB19 significantly reduced the basal expression of flTF as well as HTF. Pretreatment of cells with KH-CB19 or TG003 led to a reduction of the TNF-α-induced increase in phosphorylation of all analyzed SR proteins compared with TNF-α-stimulated controls [1].