Cdk5 phosphorylates δ-catenin on serines 300 and 357. A, Peptides representing seven putative Cdk5 consensus phosphorylation sites used in in vitro kinase assays in which the source of the kinase was immunoprecipitated from adult mouse brain. The bar graph on the left showed phosphorylation of peptides 1 and 6, and the bar graph on the right showed the positive control NF-H peptide phosphorylation. B, Peptides representing seven putative Cdk5 consensus phosphorylation sites used in in vitro kinase assays in which the source of the kinase was recombinant p35/Cdk5. Specific activity was understandably higher in these assays. The bar graph on the left showed phosphorylation of peptides 1 and 6, and the bar graph on the right showed the positive control NF-H peptide phosphorylation. C, Peptides representing seven putative Cdk5 consensus phosphorylation sites used in in vitro kinase assays in which the source of the kinase was Cdk5 immunoprecipitated from Cdk5 knock-out (KO) and wild-type lysates (WT). The last two bars represent the positive control NF-H peptide phosphorylation.