CCND1 (cyclin D1), also known as PRAD1 or BCL1, belongs to the highly conserved cyclin family, whose members are characterized by a dramatic periodicity in protein abundance throughout the cell cycle. CCND1 forms a complex with and functions as a regulatory subunit of CDK4 or CDK6, whose activity is required for cell cycle G1/S transition. The CCND1 gene, located on 11q13 has been reported to be overexpressed in mantle cell lymphoma (MCL) due to the chromosomal translocation. CCND1 has been shown to interact with tumor suppressor protein Rb and the expression of this gene is regulated positively by Rb. Over-expression of CCND1 is known to correlate with the early onset of cancer and risk of tumor progression and metastasis.