CCND1 and breast cancer: Cyclin D1 promotes progression through the G1-S phase of the cell cycle by phosphorylating and inactivating the retinoblastoma protein and its over-expression has been linked to early onset of cancer and increased risk of tumour progression and metastasis in parathyroid adenoma, breast cancer, colon cancer, lymphoma, melanoma, and prostate cancer (reviewed in [28]).