CCND1 and breast carcinoma: Experimental data show that cyclin D1 expression can be regulated by several factors which may be dysregulated in breast cancer, including growth factors (Musgrove et al, 1993), p53 through p21WAF1 (Chen et al, 1995) and oestrogen (Musgrove et al, 1994; Altucci et al, 1996).