Our evidence suggests that educated osteoblasts, in turn, engage in crosstalk with bone-disseminated breast cancer cells via proteins (i.e., decorin and NOV) and soluble factors, among others, which lead to a reduction in breast cancer cell proliferation via an increase in the cell cycle inhibitor p21 and reduction in the number of breast cancer cells entering the S phase of cell cycle. This evidence concerns the gene DCN and breast carcinoma.