Cyclin D1 Adenovirus (Ad-Cyclin D1)

Cyclin dependent kinases (Cdks) are critical regulators of cell cycle progression that are constitutively expressed throughout the cell cycle. Family members include Cdc2 p34, Cdk2-9, PITSLRE, PCTAIRE-1-3, KKIAMRE, KKIALRE and NKIAMRE. Prototype members of this family include Cdc2 p34 and Cdk2, which function late in the cell cycle, whereas other members, Cdk4, Cdk6 and a related protein Cdc7, are critically involved in the G1 and S phase transitions. Cdks comprise the catalytic subunit of the cell cycle kinases and they associate with specific regulatory subunits to form an active complex. Cyclin H is one such regulatory subunit that preferentially binds to Cdk7 and forms the cyclin H/Cdk7 complex, which then phosphorylates Cdc2, Cdk2 and Cdk4 to regulate cell cycle progression. Cyclin D1 forms a complex with and functions as a regulatory subunit of CDK4 or CDK6, whose activity is required for cell cycle G1/S transition. This protein has been shown to interact with tumor suppressor protein Rb and the expression of this gene is regulated positively by Rb. Mutations, amplification and overexpression of this gene, which alters cell cycle progression, are observed frequently in a variety of tumors and may contribute to tumorigenesis.