Cyclin D1 in mammary carcinoma

The control of the cell-cycle-associated protein cyclin D1 and its variable behaviour in normal and transformed cells is described and contrasted with its activity in vivo. The role of cyclin D1 as a prognostic and predictive marker is examined in clinical breast cancer. High levels of the protein are seen in well differentiated, oestrogen receptor positive tumours, which respond well to tamoxifen treatment for metastatic disease. © 1997 John Wiley & Sons, Ltd.