CCND1 and breast cancer: To clarify the importance of cyclin D1 in breast cancer we therefore analysed the expression of cyclin D1 in different subcellular localisations, using a previously validated antibody [36], as well as the gene amplification status by the well-established CISH technique in a large, well-characterised randomised patient cohort including more than 1,000 patients with ER-positive breast cancers.