Cyclins and breast cancer

Cyclins are regulatory subunits for cyclin dependent kinases in the coordin ation of the cell cycle. Cyclins can also serve non-cell cycle functions, s uch as the transactivation of estrogen receptor by cyclin D. Evidence for t he participation of the G(1) cyclins D and E in breast cancer is summarized , including transgenic and knockout mice, transfections, and expression pat terns in cohort studies. Overexpression of cyclin D has been reported in du ctal carcinoma in situ (DCIS), and similar overexpression of cyclin E is su ggested. Strategies to reduce cyclin expression are discussed as potential prevention efforts.