Rat Cyclin-dependent Kinase 4, CDK-4 ELI

Ser/Thr-kinase component of cyclin D-CDK4 (DC) complexes that phosphorylate and inhibit members of the retinoblastoma (RB) protein family including RB1 and regulate the cell-cycle during G(1)/S transition.

Phosphorylation of RB1 allows dissociation of the transcription factor E2F from the RB/E2F complexes and the subsequent transcription of E2F target genes which are responsible for the progression through the G(1) phase.

Hypophosphorylates RB1 in early G(1) phase.

Cyclin D-CDK4 complexes are major integrators of various mitogenenic and antimitogenic signals.

Also phosphorylates SMAD3 in a cell-cycle-dependent manner and represses its transcriptional activity.

Component of the ternary complex, cyclin D/CDK4/CDKN1B, required for nuclear translocation and activity of the cyclin D-CDK4 complex (By similarity).