Figure 3.

Putrescine induces Cdk5 activity and p35 expression. A, Representative images of a Cdk5 kinase assay (n = 3). CGNs were treated with 100 μm putrescine for the times indicated, and Cdk5 was immunoprecipitated. Cdk5 activity was assessed by combining the immunoprecipitated Cdk5 with ³²P and histone H1 and measuring the incorporation of ³²P by autoradiography. B, Western blots of CGNs treated with 1 mm dbcAMP for the times indicated (n = 5). C, Western blots of CGNs treated with 100 μm putrescine for the times indicated (n = 3). Graphs represent densitometric measurements that have been normalized to the control (0 h time point) and depicted as average fold changes ± SEM. *p < 0.05; **p < 0.01.