Regulation of pancreatic β-cell function by Cyclin-Dependent Kinase 5 (CDK5). Cyclin-Dependent Kinase 5 (CDK5) is overactivated by high glucose or by signal downstream of tyrosine kinase receptor. The PDX 1 is translocated from nucleus to cytoplasm due to activation of CDK5. That results in the suppression of gene expression by induction of transcription factors such as CCAAT enhancer binding protein β, which acts as negative regulator of insulin gene transcription.