CyclinD1 Protein

CyclinD1 is a member of the cyclin family of proteins that are important regulators cyclin-dependent protein kinases (CDKs) (1). CyclinD1 forms a complex and functions as a regulatory subunit of CDK4 or CDK6 which are important during cell cycle G1/S transition. CyclinD1 has been shown to interact with the tumor suppressor protein Rb and the expression of CyclinD1 is positively regulated by Rb. Mutations, amplification and overexpression of CyclinD1 have been frequently observed in a variety of tumors and suggesting a role of this protein in tumorigenesis (2).