PDA-66 does not inhibit GSK3β kinase activity. Recombinant human GSK3β was incubated with pGS2, ATP and different concentrations of PDA-66 and SB-216763. While treatment with the known GSK3β inhibitor SB-216763 lead to a stable reduction of enzyme activity with significant alterations at 5 μM PDA-66 showed only a slight inhibitory potential. Results are displayed as the mean ± SD of five independent experiments. In each experiment the concentrations of PDA-66 and the control were tested with 4 replicates. RLU = relative luminescence units. *Significant treatment effect vs. DMSO control, α = 0.05.