ML167 is a highly selective inhibitor of Cdc2-like kinase 4 (Clk4) with IC50 value of 136nM [1].

The Clk family enzymes play their roles in gene splicing via phosphorylating the major component of the spliceosome, SR proteins. Small molecule probes that target Clk’s can be used to study the modulating functions of these kinases in gene splicing. ML167 is found as the first fully selective inhibitor of Clk4 but not other related kinases including Clk1, Clk2 and Clk3 and Dyrk1A/1B. It is 10-fold more potent against Clk4 over other kinases. The treatment of ML167 on Caco-2 cells proves that ML167 is highly cell-permeable. Besides that, ML167 is also found to be an ATP-competitive inhibitor [1].

References:
[1] Rosenthal A S, Tanega C, Shen M, et al. An inhibitor of the Cdc2-like kinase 4 (Clk4). 2011.