Figure 4

Traditional kinase assay: γ-³²P incorporation into target and control peptides. Kinase assays were prepared with target peptides 2B-Sp, 2B-S, 2B-A, and γ-³²P labeled ATP. Incorporation of γ-³²P into each peptide was quantified in counts per minute (cpm) by liquid scintillation counting. Assays were performed with 6.25 ng of recombinant GSK-3β, and in the absence or presence of 50 mM LiCl. An assay devoid of GSK-3β enzyme in the presence of 2B-Sp controlled for background radioactivity readings. Incorporation of radioactivity in cpm units were plotted as means +/- SEM (n = 9). * denotes statistical significance by ANOVA and Tukey's post-hoc analysis (p < 0.05).