In addition to CLK1, only two kinases have an IC50 value less than 100 nM, namely CLK2 (IC50: 31 nM) and CLK4 (IC50: 8 nM), DYRK1A is the strongest off-target. The effects of CLK1-IN-1 on yellow LC3 puncta also displays obvious dose dependency, and a dose of 10 μM shows the best performance. In addition, in CLK1-IN-1-treated cells, the number of red LC3 puncta (mRFP signals only35) increases compared with that of DMSO-treated cells, indicating the formation of autolysosomes. Importantly, CLK1-IN-1 stimulates the degradation of SQSTM1/p62 and increases the ratio of red LC3 puncta to yellow LC3 puncta, both of which indicate induction of autophagic flux by CLK1-IN-1.

APAP exposure results in severe liver injury and treatment with CLK1-IN-1 (i.p., 30 mg/kg) imparts a significant hepatoprotective effect. Treatment with CLK1-IN-1 decreases serum ALT and AST levels significantly such that both marker enzymes return to normal levels.