The Cdc2-like kinases (Clks) and the dual-specificity tyrosine phosphorylation-regulated kinases (DYRKs) are involved in regulating gene splicing. Clks phosphorylate serine/arginine-rich proteins, which are a major component of the spliceosome, whereas DYRKs interact with and activate splicing factors. ML167 is a selective, ATP-competitive inhibitor of Clk4 with an IC50 value of 136 nM. It is more than 10-fold less active against the closely related kinases Clk1-3, DYRK1A, and DYRK1B (IC50s = 1.5, 1.6, >10, >10, and 4.4 μM, respectively), and minimally active against a panel of other kinases.
