These include reports showing a lack of correlation between cell proliferation and cyclin D1 expression in several large cohorts of 779 breast cancer patients [45,46] and the fact that elevated cyclin D1 expression is associated with a high incidence of metastasis and poor survival outcome [47,48], suggesting that cyclin D1 may play a role in promoting invasiveness of established tumors. This evidence concerns the gene CCND1 and breast carcinoma.